Alan Rickman was hand picked to play Snape by J.K. Rowling, and received special instruction from her as to his character. Rowling even provided him with vital details of Snape's backstory, not revealed until the final novel.

The child actors and actresses would do their actual schoolwork in the movie, to make the school setting more real.

Warner Brothers originally considered making the entire "Harry Potter" film franchise as a set of computer animated films, or attempting to combine several of the novels into a single movie. The studio's reasoning mainly had to do with concern over the rapid aging of child actors and actresses, if production ran too long on any of the films, or if production was delayed between sequels, the leading actors and actresses might have to be re-cast. Author J.K. Rowling vetoed both of the ideas of combining books, and an animated film, so the studio decided instead to produce all eight films back to back, so the same actors and actresses could play their roles in every film.

The Restricted Section scene was filmed in the Duke Humfrey's building at the Bodleian Library in Oxford. They have very strict rules about not bringing flames into the library. The makers of Harry Potter were the first ever to be allowed to break this rule in hundreds of years.

The filmmakers originally wanted to use Canterbury Cathedral as a filming location for some of the Hogwarts scenes, but the Dean of Canterbury refused to allow it, saying that it was unfitting for a Christian church to be used to promote pagan imagery. Gloucester Cathedral agreed to take its place; the Dean of Gloucester, the Very Reverend Nicholas Bury, admitted to being a fan of the books. Nonetheless, there was a huge media outcry in Gloucester when it was decided to use the local Cathedral as a filming location. Protesters wrote letters by the sack load to local newspapers, claiming it was blasphemy, and promising to block the film crew's access. In the end, only one protester turned up.

The inscription around the Mirror of Erised says: "Erised stra ehru oyt ube cafru oyt on wohsi". Reading the inscription backwards it says, "I show not your face, but your heart's desire."

The filmmakers attempted to go the extra mile of matching the kid's appearances to how the novel describes them, by fitting Daniel Radcliffe (Harry Potter) with green-colored contact lenses, and similarly make Emma Watson (Hermione Granger) wear fake buck teeth. But when Dan's eyes reacted strongly to the contacts, and Emma couldn't talk clearly with the fake teeth in her mouth, these ideas were dropped.

Producer and Director Chris Columbus has stated in interviews, that he was disappointed with the visual effects in this film, saying that they were "rushed" and "never up to anyone's standards," and sought to improve them for Harry Potter and the Chamber of Secrets (2002). This did not, however, prevent the film from being nominated for a BAFTA award for "Best Visual Effects".

In order to make the Dursleys' house even more unpleasant, Set Decorator Stephenie McMillan deliberately sought out the ugliest furnishings possible.

The Hogwarts' motto, "Draco dormiens nunquam titillandus", means "never tickle a sleeping dragon".

In the film, the scar on Harry's forehead is off-center. This was done at J.K. Rowling's request. Due to the artwork on the covers of her books, many people have assumed that his scar is supposed to be in the center of his forehead. The books, however, never specify exactly where on his forehead the scar is located.

Tom Felton did not read any of the Harry Potter books before auditioning, and at the audition, Chris Columbus was asking each contender for the role of Malfoy, what his favorite part in the book was. When it was his turn, Felton said his favorite part in the book was the part at Gringrotts, which is what the previous contender had just said. Chris saw through this very quickly, and thought it was very funny.

Platform 9 3/4 was filmed at King's Cross, but on platforms 4 and 5. J.K. Rowling has admitted that she mixed up the layout of London's King's Cross railway station when she assigned the Hogwarts Express to platform 9 3/4, reached by using magic between platforms 9 and 10. She meant the location to be in the inter-city part of the station, but 9 and 10 are actually among the rather less grand suburban platforms. The movie conformed to the book: the platforms seen as 9 and 10 are, in real-life, inter-city platforms 4 and 5. However, there is, in fact, a "Platform 9 3/4" at King's Cross. It's located in the walkway area between the real platforms 9 and 10, as a treat for fans of Harry Potter.

West Anglia Great Northern Trains, the company that owns "Platform 9-3/4", affixed one-quarter of a luggage trolley forwardly "disappearing" into the wall so as to allow fans (and their parents) to take pictures of themselves seeming to disappear into the wall.

Sir Richard Harris had trouble remembering his lines, and Daniel Radcliffe would ask him to help with running his lines, just to give Richard more practice.

Robbie Coltrane was the first person to be cast.

J.K. Rowling revealed on her website that she was considered to play Lily Potter during the Mirror of Erised scene, but she turned down the role, which instead went to Geraldine Somerville.

In the script, the flashbacks to Voldemort killing Harry's parents were written by J.K. Rowling. The producers knew she was the only one who knew exactly what happened.

At the time this film was in production, only four of the seven books had been published. J.K. Rowling was retained as a consultant on the film, not only to ensure consistency with the first book, but also to avoid conflicts with her vision for the later entries. It has been confirmed, that at least one line of dialogue was removed from the script, to avoid a contradiction with the then-unpublished "Harry Potter and the Order of the Phoenix".

The scenes at Hagrid's Hut were filmed on-location, albeit in a small patch of land in London, not far from Leavesden Studios. The hut was demolished, when the shoot wrapped, in case fans of the film swamped it.

When holding auditions for the role of Hermione, the casting team travelled around to local British primary schools to hold auditions in the hopes to find their actress. When they arrived at Emma Watson's school, she had no desire to audition, despite nearly every girl in her school wanting to. It was encouragement from her teacher, to at least attempt the audition, that made her the last girl to audition of her school.

The last name "Dumbledore" means "Bumblebee" in Old English. Also, according to the factoid trivia show QI (2003), the word "Muggle" existed in the early to mid 1900s, as a "jazz word" that was used for pot smokers.

The movie, as well as the novel, are known as "Harry Potter and the Philosopher's Stone" everywhere except the U.S., and so, every scene in which the Philosopher's Stone was mentioned, was filmed twice (once with the cast members saying "Philosopher's", and once with them saying "Sorcerer's"), or redubbed (notably, one of the times Hermoine says it in the library, her face isn't shown). The reason for this, was to keep the film consistent with the book: the U.S. publisher, Scholastic, had changed the title (and corresponding text) to "Sorcerer's Stone". The title change was done with the consent of J.K. Rowling, but she has since said, that she regrets having granting permission, and as a fledgling author, she wasn't in a strong enough position to fight it at the time.

Nicolas Flamel, mentioned as the creator of the Philosopher's (Sorcerer's) Stone, has figured as a plot device in novels featuring characters such as, Batman, Indiana Jones, and Robert Langdon of The Da Vinci Code (2006). He was (possibly) a real alchemist (born in France around 1330) who was believed by some people to have produced the Philosopher's Stone. Since there were mysterious circumstances surrounding his death in 1418, it has been rumored that he lived for hundreds of years. The book and movie gets his age right.

Rosie O'Donnell and Robin Williams were two of the celebrities who had asked for a role in the movie without pay, in their cases, Hagrid and Molly Weasley. They didn't get these roles, because J.K. Rowling wanted a strictly British and Irish cast.

The floating candles in the Great Hall were created using candle-shaped holders containing oil and burning wicks and suspended from wires that moved up and down on a special effects rig to create the impression that they were floating. Eventually one of the wires snapped, due to the heat of the flame, causing the candle to fall to the floor. Fortunately, no one was injured, but the decision was made to re-create the candles using CGI for the following films, as using real candles was determined to be a safety hazard.

During filming, Daniel Radcliffe changed the screen language on Robbie Coltrane's mobile phone to Turkish. Coltrane had to phone Hair Designer Eithne Fennel's Turkish father in order to find out Turkish for "change language".

The film reveals that the twelfth use for dragon's blood is an oven cleaner.

In order to give Hogwarts Castle an authentic look and feel, much of the filming was done at locations around England, including Christ Church, Oxford, Durham Cathedral, Gloucester Cathedral, and Alnwick Castle. In fact, the only sets that were built for Hogwarts were the Great Hall, the Grand Staircase, and the Gryffindor Common Room. In the later films, additional sets would be built for the various classrooms and other locations around Hogwarts.

Hagrid is eight feet six inches tall.

Three owls play Hedwig: Gizmo, Ook, and Sprout, but mainly Gizmo.

The tabby cat, used in the movie, ran away during filming, and came back two days later.

J.K. Rowling insisted that the principal cast be British, and she got her wish, with two main exceptions, Sir Richard Harris was, of course, Irish, and Zoë Wanamaker, though she has made her name as a "British" actress, was actually born in the United States. Other non-Brits in the cast include Verne Troyer, born in Michigan, plays Griphook, but he's dubbed by a Brit; and Chris Columbus' daughter, Eleanor Columbus, who played Susan Bones, though she never says a word. It's also been noted that Emma Watson was born in France, to British parents.

Sir Richard Harris only agreed to taking the part of Albus Dumbledore after his eleven-year-old granddaughter threatened never to speak to him again. Patrick McGoohan was originally offered the role, but had turned it down, due to health reasons. Coincidentally, Harris had health issues of his own, dying of Hodgkin's lymphoma shortly before the release of Harry Potter and the Chamber of Secrets (2002).

Throughout the Harry Potter franchise, Daniel Radcliffe went through one hundred sixty pairs of glasses.

The platform attendant, at King's Cross, who asks Harry, "You think you're funny, do you?" actually works for GNER. He is, however, a train manager, and not a platform attendant.

The floor in the great hall is made of York stone. Production Designer Stuart Craig had the foresight to invest a significant amount of his design budget on the stone. While this decision was questioned at the time, it proved to be a wise one, as the stone was durable enough to withstand the footsteps of hundreds of actors and actresses, as well as several camera crews, over the next decade to film the entire series.

By February 2002, this was the second highest grossing film worldwide after Titanic (1997).

In this film, all the food that you see in the Great Hall feasts are real. Chris Columbus wanted a very elaborate welcome feast to match the description in the book, with roast beef, ham, turkey, and all the trimmings. Unfortunately, filming under the hot stage lighting, for hours at a time, quickly caused the food to develop an unpleasant odor, despite the meat being changed every two days and the vegetables twice a day. For the following films, samples of real food were frozen, so that molds could be made of them, and copies cast in resin.

In the trophy cupboard, to the right of the Quidditch trophy, you can see the "Service to the School" trophy with part of "Tom M. Riddle" engraved on it; the trophy and the name on it are confirmed by Ron in a deleted scene from Harry Potter and the Chamber of Secrets (2002).

The Wizard's chess set, with which Harry and Ron were playing, in the Great Hall, is based on the Lewis Chessmen, which date from the twelfth Century. They were found in 1831, on a beach on the Isle of Lewis, Outer Hebrides, Scotland. In all, ninety-three pieces were recovered, with eleven now residing at the National Museum of Scotland in Edinburgh, and eighty-two at the British Museum in London.

On the Quidditch trophy, that has Harry's father's name on it, there are additional inscriptions for M. McGonagall and R.J.H. King. The latter being a reference to John King, the Supervising Art Director on the film.

The troublemaking poltergeist Peeves (played by Rik Mayall) does not, in the end, appear in the movie, nor in deleted scenes on any home editions of the film. Mayall claimed he didn't find out that he was cut from the film, until he saw the movie. Ultimately, Peeves was never used in any of the Harry Potter films. Mayall claimed that he was cut, because the young actors and actresses kept laughing at his performance.

Neville received a remembrall from his grandmother, but he doesn't remember what he has forgotten. In that scene, Neville is the only student without his robe on. He must have not remembered to put his robe on.

Julie Walters has said if had she known that fellow Midlander Mark Williams would be cast as Molly Weasley's husband Arthur in the following film, then she would have played up their shared accent, feeling that this would have helped signpost their family's perceived uniqueness in the magical world.

Liam Aiken was originally given the role of Harry, but a day later the offer was revoked, when it was discovered that he wasn't British (Aiken had previously worked with Chris Columbus).

In addition to Steven Spielberg, other candidates for the director's chair were Jonathan Demme, Terry Gilliam, Mike Newell, Alan Parker, Wolfgang Petersen, Rob Reiner, Ivan Reitman, Tim Robbins, Brad Silberling, M. Night Shyamalan, and Peter Weir. Newell would later direct the fourth entry of the series, Harry Potter and the Goblet of Fire (2005). Gilliam was J.K. Rowling's first choice, but the studio finally picked Chris Columbus to direct, because he had experience directing child actors and actresses. Columbus was also asked many times by his daughter to direct, and he agreed after he read her copy of the book.

Robbie Coltrane's 6'10" body double for Hagrid is former England rugby international, Martin Bayfield.

James Phelps and Oliver Phelps, the twin actors who play Fred and George Weasley respectively, both have naturally dark brown hair which was dyed red for their roles. Similarly, Tom Felton's hair, which is also naturally brown, was bleached blond for his role of Draco Malfoy.

Rik Mayall only took the part of Peeves, as the children at his own kid's school were talking about the books. He later said, "The film, with respect. No, with no respect at all. The film was shit."

J.K. Rowling hand picked Robbie Coltrane, Dame Maggie Smith, and Alan Rickman for their roles.

At one point, when Harry, Ron, and Hermione are approaching Hagrid, he can be seen playing a wind instrument. He is playing Hedwig's Theme.

Warwick Davis, who played Professor Flitwick and the first Gringotts Goblin, also provided the voice for Griphook, who was physically played by Verne Troyer.

The statue of the humpbacked witch, in the corridor leading to Fluffy's chamber, is a secret entrance leading to Honeydukes.

In the second book of the series, "Nearly Headless" Nick invites Harry to his "deathday" party, celebrating the 500th anniversary of his demise in 1492 (a fact that fans have used to place the entire book chronology in the years 1991-1997). 1492, is, of course, the year that Christopher Columbus made his famous voyage to the New World; this film's production company is "1492 Pictures", a deliberate reference to Chris Columbus' famous namesake.

David Thewlis, who later played Professor Lupin in Harry Potter and the Prisoner of Azkaban (2004), was considered for the role of Professor Quirrell.

Professor Quirrell's classroom was filmed on-location at Lacock Abbey in Wiltshire, in a room known as the Warming room. The cauldron seen in the room is not a prop, but in fact came with the location. It is believed that the cauldron is over five hundred-years-old, and was used by cooks who worked for Queen Elizabeth I.

Daniel Radcliffe learned he'd won the role of Harry Potter while in the bathtub.

Harry Potter's birthday is stated in the books to be July 31, 1980, as J.K. Rowling was born on July 31, 1965. By coincidence, Richard Griffiths (Uncle Vernon) was born on July 31, 1947. Daniel Radcliffe was once reported to been born on July 31, 1989, but this was merely a publicity stunt. In fact, Radcliffe was born on July 23, 1989.

Ron's choice of opening, in the final chess match, is called Center Counter Opening (or Scandinavian Defense), which, due to its asymmetrical nature, is said to be a highly unpredictable, and difficult opening for either side, that rarely results in a draw.

When Chris Columbus was asked what type of child he wanted to play Harry Potter, he used a clip of Daniel Radcliffe from David Copperfield (1999) to show them what he wanted.

The only Harry Potter film not to feature Mark Williams, who plays Arthur Weasley.

As his audition, Rupert Grint sent a video of himself rapping while explaining why he wanted the part of Ron.

Chris Columbus was amazed how beautifully Daniel Radcliffe, Emma Watson, and Rupert Grint matured over the Harry Potter franchise, both physically, and as actors and actress, compared to some child actors and actresses, who start out adorable, and either lose that, or become bad actors and actresses as they grow older.

Almost all the scenes with Harry and/or the trio were filmed in chronological order, most notable exceptions being: The final scene in the film, where the trio return home on the Hogwarts Express, was the first scene filmed, followed by the scene when Harry first sees the locomotive at Platform 9 & 3/4 (the only other scene which required the actual train present). Then, the Quidditch match was the last thing filmed, mostly due to how long it took the effects departments to figure out how to do it.

Chris Columbus had wanted Daniel Radcliffe for the lead role since he saw him in David Copperfield (1999), before the open casting sessions had taken place, but had been told by Susie Figgis that Radcliffe's protective parents would not allow their son to take the part. Columbus explained that his persistence in giving Radcliffe the role was responsible for Figgis' resignation. Radcliffe was asked to audition in 2000, when David Heyman and Steve Kloves met him and his parents at a production of Stones in His Pockets in London. Heyman and Columbus successfully managed to convince Radcliffe's parents that their son would be protected from media intrusion, and they agreed to let him play Harry.

The exterior used for King's Cross Station, is actually St. Pancras Station, which is just down the road. This was used because the façade of St. Pancras is more visually appealing than that of King's Cross.

When filming the scenes at Gloucester Cathedral, the cathedral's modern electric signs, light switches, and door locks had to be concealed behind panels that were painted to match the rest of the stone walls. The stained glass windows were also modified to hide the fact that the building was a church; the religious symbols were covered with colored plastic filter paper to blend in with the surrounding glass. One window depicted the naked figures of Adam and Eve; they were given clothes and even the trademark Harry Potter lightning scars on their foreheads.

This movie has the highest number of Academy Award nominations for a Harry Potter movie, totalling three. The other entry to do this was the final film in the franchise, Harry Potter and the Deathly Hallows: Part 2 (2011). This is the only Harry Potter movie to be Oscar nominated for Best Costume.

The word "bloody" appears in the film six times, along with one "arse", one "bugger", and two "blasted"s. This, and some very scary scenes in the haunted forest, led to its PG rating.

Troll (1986) features a character called Harry Potter, who fights trolls, and casts spells. It came out eleven years before J.K. Rowling published "Harry Potter and the Philosopher's (Sorcerer's) Stone". J.K. Rowling denies any connection.

The street, down which Harry and Hagrid walk, to get to the Leaky Cauldron, is the same street on which Sir Sean Connery was parked, waiting for Catherine Zeta-Jones to leave the antiques shop in Entrapment (1999).

Daniel Radcliffe said that he didn't think that he would play Harry in all of the films, as he believed he wouldn't fit the part, once he got older. However, he went on to star in all eight movies.

In the flying lesson, the whistle Madame Hooch is wearing, is called a "Boatswain's Call" and was originally used in the early Navy (before P.A. systems) to signal an order, because the whistle could be heard from one end of the ship to the other. It is now used in the Navy as a ceremonial whistle.

Casting Harry Potter was the film's biggest challenge; they saw five thousand auditions, and none of them felt right. Chris Columbus saw Daniel Radcliffe in David Copperfield (1999), and showed it to the Casting Director, and said Radcliffe was the one, and that he was amazing. But she said they wouldn't get him, because his parents want him to focus on his schoolwork, and not acting, as well as all the attention he'd get. So they interviewed Harry Potter's of different nationalities all over the world, and still hadn't found him. She got frustrated with Columbus, because he had his heart set on Radcliffe. By sheer coincidence, the Producer and Screenwriter of this movie went the theater, and in the front row was Radcliffe, with his father, so they talked, and slowly persuaded him to cast Radcliffe.

Steve Kloves was nervous when he first met J.K. Rowling, as he did not want her to think he was going to "destroy her baby". Rowling admitted that she "was really ready to hate this Steve Kloves", but recalled her initial meeting with him: "The first time I met him, he said to me, 'You know who my favorite character is?' And I thought, 'You're gonna say Ron. I know you're gonna say Ron'. But he said "Hermione", and I just kind of melted."

Hatty Jones auditioned for Hermione Granger before it went to Emma Watson. She and Emma were the last girls for the audition.

At one point, Harry mentions that during his trip to London, he heard Hagrid profess his love for dragons and his desire to own one. The scene that Harry describes was filmed, but deleted from the movie.

This movie has the distinction of opening on more screens in the U.S. than any other (3,762).

The owls used in the film were shipped over from Massachusetts.

Daniel Radcliffe was initially meant to wear green contact lenses as his eyes are blue, and not green like Harry's, but the lenses gave Radcliffe extreme irritation, and, upon consultation with J.K. Rowling, it was agreed that Harry could have blue eyes.

James Horner was contacted to compose the music for the film, but he was unavailable, because of his schedule conflict. The task ultimately went to John Williams.

All of the cars on Privet Drive are Vauxhalls, no matter the time period. The Dursleys own a silver 2000 Vauxhall Vectra Estate. All of the other cars parked in the drives are Vectra Estates in the present day, with Astra, Belmont, and Cavalier Saloons from the late 1980s in the pre-title prologue.

Tim Roth was a leading contender for the role of Professor Severus Snape. Roth dropped out of contention, however, to pursue his role as General Thade in Tim Burton's adaptation of Planet of the Apes (2001).

Screenwriter Michael Goldenberg wrote a draft of the script, but was ultimately rejected by David Heyman, in favor of Steve Kloves' draft. Heyman, however, was impressed with his draft, and was subsequently brought in to write the script for Harry Potter and the Order of the Phoenix (2007), when Kloves backed out to commit to a personal project.

For the Gringotts interior scenes, the Australian High Commission in London was used. The exteriors are the Silver Vaults located not far from the Australian High Commission.

Chris Columbus, remembering his experiences with Macaulay Culkin during the production of Home Alone 2: Lost in New York (1992), would only audition child actors and actresses without "stage parents" during casting.

The only Harry Potter movie not to feature a stylized version of the Warner Brothers logo, although the film's theme is played over the standard logo, as opposed to the original Warner Brothers theme.

Crabbe and Goyle have no dialogue.

Emma Watson has stated that she hates the way her hair looks in this film. In the following films, her hair was made less bushy, and more wavy.

In the original draft, Drew Barrymore, a self-proclaimed Harry Potter fan, had a cameo.

The design for the Great Hall set was based on the hall at Christ Church, Oxford. Oxford University also served as a filming location.

Despite having less than a minute of screentime, and only two lines of dialogue, the unnamed Head Goblin at Gringotts is featured prominently on the American theatrical poster, right under Ron and Harry's faces. It is thought by many, that this is because of his rather striking appearance.

Emma Watson's Oxford theater teacher passed her name on to the casting agents, and she had to do over five interviews before she got the part. Watson took her audition seriously, but "never really thought I had any chance of getting the role." The producers were impressed by Watson's self-confidence, and she outperformed the thousands of other girls who had applied.

Despite the objection to the Harry Potter series by certain Christian groups, several historic churches in the UK, including Durham Cathedral, Gloucester Cathedral, Lacock Abbey, Christ Church College Oxford, and in the later films, St. Paul's Cathedral, were used as filming locations for the franchise. They even inspired much of the layout and architectural details of Hogwarts.

Judianna Makovsky re-designed the Quidditch robes, having initially planned to use those shown on the cover of the American book, but deemed them "a mess". Instead, she dressed the Quidditch players in "preppie sweaters, nineteenth century fencing breeches, and arm guards."

The "Hogwart's Express" locomotive portrayed in this film, a 1937 4-6-0 "Hall" class steam engine number 5972, originally belonged to the Great Western Railway and went under the name of "Olton Hall".

John Williams composed a piece of music specifically for the movie's trailer without having seen a single frame of film, and it is found on the soundtrack as "The Prologue". As of March 2002, he has done this only once before, for Steven Spielberg's Hook (1991). (However, on the collector's edition of the soundtrack for Jaws (1975), a previously unreleased track appears called "Shark Attack", which was only used in the trailer for that movie, in 1975.)

In the book, Hermione is described as having buck teeth. This was abandoned when Emma Watson couldn't speak with them.

In order to understand what he believed to be caretaker Filch's lonely lifestyle, David Bradley and his cat rented an isolated Irish cottage, in which to live for a month, before filming began.

In the warehouse section of the National Railway Museum in York, there is an apparently authentic and suitably pitted and rusty white-on-orange sign saying "Platform 9 3/4", in the style that British Railways used in the 1950s and 1960s.

This and Harry Potter and the Chamber of Secrets (2002) are Chris Columbus' two biggest financial hits.

The highest grossing film of 2001.

The film cast includes one Oscar winner: Dame Maggie Smith; and four Oscar nominees: Sir Richard Harris, Sir John Hurt, Julie Walters, and John Cleese.

Film debut of Emma Watson.

Chris Columbus pitched his vision of the film for two hours, stating that he wanted the Muggle scenes "to be bleak and dreary" but those set in the wizarding world "to be steeped in color, mood, and detail." He took inspiration from Great Expectations (1946) and Oliver Twist (1948), wishing to use "that sort of darkness, that sort of edge, that quality to the cinematography," taking the color designs from Oliver! (1968) and The Godfather (1972).

Scenes from Chris Columbus' script for Young Sherlock Holmes (1985) were used in auditioning the young actors and actresses.

In the troll scene, in the girl's bathroom, Daniel Radcliffe isn't actually on the troll's neck, because the motions would have snapped his neck; therefore, his image was digitally added.

After Steven Spielberg dropped out, he recommended M. Night Shyamalan for the project, but he ultimately turned it down.

Daniel Radcliffe was reportedly paid one million pounds for the film, although he felt the fee was not "that important".

Filming started in September 2000, and finished on March 21, 2001.

Simon Fisher-Becker says he signed a four-picture deal to play the Fat Friar, but this was the only film he did, and nearly all of his role was removed in post-production.

When the directors first came to J.K. Rowling to ask if they could make movies on the entire Harry Potter series, she said yes, but on one condition. She said that as she imagined all the characters to be British, all of the actors and actresses have to be British.

Dudley Dursley is played by Harry Melling. There is a brief moment in the film, which was not in the book, in which Hagrid mistakes Dudley for Harry, to which Dudley responds that he's "not Harry".

Chris Columbus wanted to work with Director of Photography John Seale, and asked the studio to hire him, but at that time, Seale was committed to shooting Timeline (2003). However, production delays, for the latter film, enabled Seale to be available for this movie's photography period.

Chris Columbus originally planned to use both animatronics and CGI to create the film's magical creatures, including Fluffy.

Much of the stonework around Hogwarts (excluding the areas that were filmed on-location) is actually plaster that has been painted and distressed to make it appear as though it is hundreds of years old.

Apart from Peeves the Poltergeist, two other minor characters from the book did not make it into the film. The first is Mrs. Arabella Figg, Harry's friendly elderly neighbor from across the street, who is described in the early chapter of the book. Although she was omitted from the first four movies, she finally appears in Harry Potter and the Order of the Phoenix (2007). The second character to be omitted is Professor Binns, Hogwarts' teacher of History of Magic. The book describes him as the only teacher who is a ghost, seemingly being quite unaware of the fact that he died in his sleep.

There is a painting of Anne Boleyn hanging in Hogwarts, to the right of the staircase just before Harry, Ron, and Hermione encounter Fluffy for the first time. Anne Boleyn was Henry VIII's second wife, beheaded for the supposed crimes of treason, incest, and witchcraft.

Sir Richard Harris, who had been acting for over forty years by the time this film entered production, stated that he had never been involved with a cast that was as close as this one.

William Moseley, who was later cast as Peter Pevensie in The Chronicles of Narnia movies, also auditioned for the role of Harry Potter.

The movie features nearly six hundred visual effects shots, involving numerous companies.

For most of the film, the body double for Hagrid would wear a animatronic head that resembled Robbie Coltrane. The head is displayed at the Harry Potter Studios in London.

Although Steven Spielberg initially negotiated to direct the film, he declined the offer. Spielberg reportedly wanted the adaptation to be an animated film, with Haley Joel Osment to provide Harry Potter's voice, or a film that incorporated elements from subsequent books as well. Spielberg contended that, in his opinion, it was like "shooting ducks in a barrel. It's just a slam dunk. It's just like withdrawing a billion dollars and putting it into your personal bank accounts. There's no challenge." J.K. Rowling maintains that she had no role in choosing directors for the films, and that "anyone who thinks I could or would have vetoed him (Spielberg) needs their Quick-Quotes Quill serviced." David Heyman recalled that Spielberg decided to direct A.I. Artificial Intelligence (2001) instead.

Fluffy the three-headed dog's appearance is physically based on a Staffordshire Bull Terrier.

Sir Alec Guinness was considered to play the role of Dumbledore, but he died shortly before filming began.

This is the only Harry Potter movie where Harry does not cast an attacking spell.

David Heyman began the process of adapting the book into a film before it was even published.

Gabriel Thomson was considered for the role of Harry. His My Family (2000) co-star Zoë Wanamaker plays Madame Hooch.

The ornate ceiling of the Great Hall (including the trusses) was created entirely using CGI. In real-life, the ceiling consisted of nothing but studio stage lighting.

Dancing with the Stars (2005) pros Mark Ballas, Derek Hough, and Julianne Hough made uncredited cameos as Hogwart's students.

J.K. Rowling made up the names of the four Hogwarts houses while on a plane. She wrote them down on a barf bag (empty, fortunately) so she would remember them.

Caio César, a prominent Brazilian voice actor, who dubbed Daniel Radcliffe as Harry Potter, and in other films, was also a military cop, and died at the age of twenty-seven in 2015, after being shot in the neck, at the Complexo do Alemão slums, in Rio de Janeiro.

Warner Brothers had initially planned to release the film over the July 4, 2001 weekend, making for such a short production window, that several proposed directors pulled themselves out of the running. However, due to time constraints, the date was pushed back to November 16, 2001.

Steve Kloves described adapting the book as "tough", as it did not "lend itself to adaptation as well as the next two books."

Fluffy, the three-headed dog, was modelled after Cerberus, the three-headed dog of the underworld, from Greek mythology.

Once in an interview, Rik Mayall (the voice of Peeves), said he hadn't read the book and claimed that he did to his agent, and it was one of his favorites. On the set, when asked to read his lines, he constantly made the children burst into laughter with his voice, which had got out of hand, and he was asked to turn his back to the kids to read it, which was also useless. Then they asked him to go all the way to the other side of the cathedral, and shout his words, which also caused them to laugh. According to him, Peeves was in the movie, but after a few weeks, they decided to take his scenes out. He said that when his children saw the movie, and came back home, they said to him: "That was bloody good make-up. You didn't look like yourself at all. It was really good." He said that they had mistaken him for Hagrid. He also said that the "movie was shit" because he wasn't in it.

When Chris Columbus scripted Young Sherlock Holmes (1985), that film featured similarities to his future association with the Harry Potter film franchise; the teenage Watson resembles Harry Potter; school experiments; Draco Malfoy's rivalry with Harry is similar to one Holmes has with another student, Dudley; Draco and Dudley both come from rich parents; cavernous libraries; sweets; train stations; the novelization uses the word potty, or Potter; students being injured and needing to see the school nurse; teachers and students eating in the Great Hall; Holmes, Watson, and a third character solving mysteries at school and Harry, Ron, and Hermione doing the same at Hogwarts; staircases; Harry, Holmes, and Watson creeping through a school library at night; both Watson and Hagrid say "sorry about that"; the end of school term; the threat of expulsion; no family for Harry to return to, even at Christmas; Harry has a scar on his forehead and Holmes has one on his cheek; seemingly innocent teaching staff exposed as the opposite; head boys, et cetera.

John Williams composed the score at his houses in Los Angeles and Tanglewood before recording it in London in August 2001.

Fiona Shaw, who portrays a woman despising the supernatural and witchcraft, in this film, ironically portrayed a powerful witch in True Blood (2008).

Daniel Radcliffe's second film.

Tom Felton originally auditioned for both Harry and Ron, before getting the part of Draco.

Simon Fisher-Becker signed a four-picture deal to play the Fat Friar. However, he only appears in one scene in this film, and not in any others.

If one looks at old seventeenth century maps of London, Muggle Street exists near Shakespeare's Theater, a possible influence for the word.

John Coppinger stated that the magical creatures that needed to be created for the film had to be designed multiple times.

When Chris Columbus scripted Young Sherlock Holmes (1985), Watson believed Holmes obsessed over a case, even at Christmas, because unlike other boys his age, he had no family to which to go home, like Harry Potter, or Kevin McCallister. Columbus has ties to both the Harry Potter and Home Alone franchises.

In the Wizard Pub, Harry and Hagrid go into the bar, the bartender says, "usual I presume" to Hagrid. This is possibly a reference to the books, where Hagrid would frequently get drunk.

Robbie Coltrane and Geraldine Somerville had previously costarred in Cracker (1993). However, they have no scenes together here.

Throughout the eight movie franchise, five actresses played "Pansy Parkinson": 1-Katherine Nicholson (this movie and Harry Potter and the Chamber of Secrets (2002), uncredited in both), 2-Genevieve Gaunt (Harry Potter and the Prisoner of Azkaban (2004)), 3-Charlotte Ritchie (Harry Potter and the Goblet of Fire (2005), originally listed as "Student" and uncredited), 4-Lauren Shotton (Harry Potter and the Order of the Phoenix (2007), again uncredited as Pansy), and, 5-Scarlett Byrne in Harry Potter and the Half-Blood Prince (2009), Harry Potter and the Deathly Hallows: Part 1 (2010), and Harry Potter and the Deathly Hallows: Part 2 (2011).

When Dumbledore is announcing team points, two candles can be seen rapidly floating.

Model Lucy Elgee-Taylor appeared in the background of the scene in the great hall.

Among the numerous directors who were interested in tackling the film were Simon West, Brad Silberling, Robert Zemeckis, Jonathan Demme, Jan de Bont, and Joel Schumacher.

Chris Columbus released Home Alone (1990) on November 16, 1990, exactly eleven years sooner.

The only Harry Potter movie that features a set of triplets [the Saunders Triplets (Baby Harry Potter, born 8/30/1999)] and a set of twins [James Phelps and Oliver Phelps (Fred and George Weasley, respectively, born 2/25/1986)].

The first of eight movies based on the Harry Potter book series by J.K. Rowling.

This was the first of two (uncredited) appearances for Katherine Nicholson as Pansy Parkinson: this movie and Harry Potter and the Chamber of Secrets (2002). She was the first of five actresses to play the role.

Chris Columbus sold scripts to Steven Spielberg for Gremlins (1984) and The Goonies (1985) but his career didn't fully take off until the massive successes of Home Alone (1990) and Mrs. Doubtfire (1993) which led to the even greater success of the Harry Potter franchise.

Hermione was supposed to have buck teeth but Emma Watson thought it looked weird and found it hard to talk. The only part in the Harry Potter movies where she is wearing false teach is in the last scene on Harry Potter and the Sorcerers Stone.

Despite many instances of Harry being noted as a "great wizard", Harry does not, in fact, cast a single spell during the entire movie.

During Harry's first Christmas at Hogwarts, Fred and George bewitched snowballs to zoom in and hit the back of Quirrell's turban. In doing so, they were unknowingly hitting Voldemort in the face.

Originally, Daniel Radcliffe was supposed to wear colored contact lenses to turn his naturally blue eyes green (as Harry is described in the books as having green eyes), but after suffering an allergic reaction to the lenses, the decision was made to drop them, and Harry's eyes remained blue for the rest of the film franchise. Similarly, Emma Watson was originally going to wear fake teeth (as Hermione is described as having large front teeth), but she couldn't speak clearly with them in, and the teeth were dropped. There is one scene in the film, in which Radcliffe and Watson are wearing their respective contact lenses and teeth; it is the final scene in the film where the trio return home on the Hogwarts Express, which actually was the first scene that was filmed.

Hermione performing magic, on the Hogwarts Express, to mend Harry's broken glasses, was not in the book, it was added for the film.

One of Chris Columbus' daughters had trouble reading, until she read Harry Potter and the Sorcerer's Stone in two days, which opened her eyes to the world of books. After reading Chamber of Secrets, she asked Columbus to make films out of them, but there were fifty other directors already interested. Columbus fell in love with the first two books too, so he sat down with Warner Brothers saying how obsessed he was with making The Sorcerer's Stone more than anything else. Columbus asked to be the last director Warner Brothers saw, which took about ten days. Columbus stayed up until three a.m. re-writing the script each day. It was already a good script, but Columbus wanted to talk about the visuals. He told Warner Brothers he had re-written the script for free, and that made an impression on them, because that didn't happen in Hollywood, where they have to be paid for everything. Because Columbus had done that without any pressure from Warner Brothers, it made the difference, and after subsequent meetings, and five weeks later, he got the job of directing it.

Hermione never flies on a broom, but in the book, she flies on a broom with Harry and Ron to catch the flying key.

In the book, Harry, Hermione, Neville, and Malfoy spend a night in the Forbidden Forest, with Hagrid, for the detention, but in the movie, Neville is replaced by Ron.

In the book, Hagrid gave Harry the flute for Christmas, which he later used to lull Fluffy to sleep.

In an extended version of the film, these scenes were added: Aunt Petunia dying Dudley's old uniform gray, so Harry could use it as his school uniform. Aunt Petunia opening eggs containing Harry's Hogwarts letters. Harry and Hagrid riding in a train car, where they talked about Hagrid wanting a dragon for a pet. An extended version of Professor Snape's potion class. After rescuing Hermione from the troll, the trio had a moment wherein Ron said to Hermione, "What are friends for?" During Christmas dinner at the Great Hall, Ron tried to comfort Harry after their experiences of looking at the Mirror of Erised. Harry, Ron, and Hermione discovered Nicholas Flamel's name in a wizard card while eating at the Great Hall. Also, Ron confronted Neville (because Malfoy had cast a spell on him), that he should learn to stand up for himself, which he did in the end, when he tried to stop the trio from leaving Gryffindor tower.

Behind-the-scenes pictures show a different design for the incarnation of Voldemort that is stuck on the back of the head of Professor Quirrell. This version has much more animalistic features, most prominently a panther-like snout and large jaw filled with big incisors. This was later changed: Ian Hart provided the voice and motion captured Voldemort's face, which was later added with computer graphics. Richard Bremmer portrayed Voldemort in the flashback to the death of Harry's parents.

During the scene where Harry sees his parents in the mirror, it was supposed to be his entire family (according to the book).

On Christmas Day, when you see the sweater Ron's mother made him, there is a yellow R, but in the book, his sweater didn't have a letter. In the book, George and Fred come into the room and complain Ron doesnt have a letter. They said "I suppose she thinks you don't forget your name. But we're not stupid. We know we're called Gred and Forge."

The fire, trapping Harry in the dungeon with Quirrel and Voldemort, was not in the book, but it was based on the colored fire Harry and Hermione face with the seven potion bottles in the novel after winning the chess game. This practical effect of the fire surrounding the dungeon was accomplished with pipes placed in the floor around the dungeon set which were lit after Ian Hart snapped his fingers.