Robin Williams and Billy Crystal were not allowed to be on the set at the same time during filming, for fear they would crack up the cast and crew, and cause major production delays.

The first full-length movie version of Hamlet ever made (using the Second Quarto (1604) text with additions from the First Folio (1623) to create an idealized "complete" Hamlet).

Kate Winslet (Ophelia) learned on the day that she had to shoot the straitjacket scene that she had just been given the role of Rose in Titanic (1997).

At four hours and two minutes, this is one of the longest Hollywood movies of all time.

Julie Christie came out of retirement to play Gertrude.

Writer and director Sir Kenneth Branagh's decision to shoot in 65mm was largely inspired by a film format seminar conducted by visual consultant Rob Hummel. Hummel convinced him to use the format because of high-resolution and certain shots could only be achieved in 65mm. Also, Branagh once said that the intention was to give a sweeping feel to the play, hearkening back to the 1960s epics like Lawrence of Arabia (1962).

Kate Winslet did not even audition for the role of Ophelia. Winslet had previously auditioned for the role of Elizabeth in Sir Kenneth Branagh's Mary Shelley's Frankenstein (1994) (the role ended up being played by Helena Bonham Carter), and Branagh was so impressed that he offered her the role in this movie without so much as a reading. Appropriately, Carter played Ophelia in Hamlet (1990).

Like others before him who simultaneously acted in and directed a movie, Sir Kenneth Branagh used an acting double, Orlando Seale, to play Hamlet during camera set-ups and rehearsals. This means Seale had to learn and perform almost the entire play with the entire cast, yet only appears on-screen as an extra, playing the part of a "Boatman".

Sir Derek Jacobi (Claudius) played Hamlet in Hamlet, Prince of Denmark (1980). He admitted that he had some difficulty with the role of Claudius, as he kept thinking Hamlet's lines. Simon Russell Beale played Hamlet on-stage.

Writer and director Sir Kenneth Branagh offered Gérard Depardieu a small part in the four-hour version of the movie out of gratitude for his active support on the release of his first feature Henry V (1989) in France (not only was he the main distributor of the movie, but also dubbed Branagh's voice in the French version).

At the end of his DVD director's commentary, Sir Kenneth Branagh revealed that Stephen Fry receives a special thanks credit because Branagh wrote the screenplay in Fry's kitchen.

When filming the flashback scene during Hamlet's "Yorick" speech, shown in vision only with no sound, writer and director Sir Kenneth Branagh's only instruction to Ken Dodd was "Okay, make us laugh", which he did.

Sir Kenneth Branagh first encountered the full length version of the play while performing in the 1992 BBC Radio production of the play with co-stars Sir Derek Jacobi and Richard Briers (who reprised their roles as Claudius and Polonius respectively in this movie). This radio performance anticipated the winter 1992 full text production of Hamlet by the Royal Shakespeare company, the one that would finally crystallize Branagh's interpretation of the character, and lead to this movie.

The soliloquies spoken by Hamlet are almost all shot in one uninterrupted cut, except for "To be, or not to be".

The title of Hamlet's play-within-a-play is "The Murder of Gonzago", which may or may not have been extrapolated from an Italian prose work. However, when asked its title by Claudius, Hamlet responds by bestowing on it a new moniker, which reflects its purpose (to "catch the conscience of the King"), he calls it "The Mousetrap".

Part of the movie was shot at Blenheim Palace, which is owned by the Duke Of Marlborough. The then-Duke John Spencer-Churchill had a very small role in the movie as Fortinbras' General.

Hugh Cruttwell was the then-Principal of the Royal Academy of Dramatic Art, in which Sir Kenneth Branagh studied. Cruttwell was on the set all the time. He came as a request by Branagh to give an objective critique for the performance of each take.

None of the palatial interiors are really the inside of Blenheim Palace. They are actually studio-built interiors. All that is actually shown of the Palace are the exterior of it, and the gardens.

One of William Shakespeare's lines is actually changed with no acknowledgment. The sorrows come line "O Gertrude, Gertrude, when sorrows come they come not as single spies, but in battalions" becomes simply "When sorrows come they come not as single spies, but in battalions," probably because Claudius delivers them in a voice-over, and we do not know to whom he is speaking. It is the only line in the movie that is changed because of the way the scene is filmed.

For more than a year, Sir Kenneth Branagh had tried shopping the project around major studios in Hollywood, but no studio was willing to finance a four-hour production, citing skepticism of the commercial viability of a William Shakespeare adaptation to a late twentieth century audience. Also, most studios were aware of the negative reviews and the commercial failure of Branagh's previously-directed movie, Mary Shelley's Frankenstein (1994), and some of them would only finance this movie if the content and the budget is cut to half. However, Castle Rock Entertainment agreed to finance the movie and to Branagh's demands (filming in 65mm, complete control over the movie, et cetera) under two conditions: a star-studded cast for the movie, and a 35mm, abridged two and a half hour version of this movie for a wider release.

For sixteen years, it was the last studio movie to be shot in the 65/70mm process until the release of The Master (2012).

This film has nine Oscar winners in the cast: Jack Lemmon (Marcellus), who won Best Actor in a Supporting Role for Mister Roberts (1955) and Best Actor for Save the Tiger (1973), Charlton Heston (The Player King), who won Best Actor for Ben-Hur (1959), Julie Christie (Gertrude), who won Best Actress for Darling (1965), John Mills (Old Norway), who won Best Actor in a Supporting Role for Ryan's Daughter (1970), John Gielgud (Priam), who won Best Actor in a Supporting Role for Arthur (1981), Richard Attenborough (The English Ambassador), who won Best Director for Gandhi (1982), Robin Williams (Osric), who won Best Actor in a Supporting Role for Good Will Hunting (1997), Judi Dench (Hecuba), who won Best Actress in a Supporting Role for Shakespeare in Love (1998) and Kate Winslet (Ophelia), who won Best Actress for The Reader (2008). Contrary to popular belief, it does not hold the record for most Oscar -winning actors in one movie. That record goes to The Player (1992), which features twelve Oscar-winning actors and one Oscar-winning director. However, most of the actors in that movie simply had brief cameo appearances as themselves, whereas this movie features a large number of Oscar winners in significant roles with considerably more screen time.

Released just six years after Hamlet (1990), which starred Mel Gibson. Ophelia was played in that movie by Helena Bonham Carter, who at the time of this movie's release, was romantically involved with writer and director Sir Kenneth Branagh. Claudius was played by Sir Alan Bates who, like Sir Derek Jacobi, came to the role having previously played Hamlet.

Before the start of principal photography, the entire cast did a complete run through of the play, what writer and director Sir Kenneth Branagh described as a sort of studio performance. This way, as they jumped around the chronology of the text during production, everyone would have a sense of where they were in the overall story.

This was Charlton Heston's only appearance in a Shakespearean film playing a character other than Mark Antony, whom he played in Julius Caesar (1950), Julius Caesar (1970) and Antony and Cleopatra (1972).

The construction of the interiors of the "Elsinore Castle" set (actually Blenheim Palace) cost $2 million. The exteriors are simply the exteriors of the palace and had already been standing since 1784.

Sir Richard Attenborough appeared in Elizabeth (1998) as William Cecil, 1st Lord Burghley, who is believed by some scholars to have inspired the character Polonius.

This was the director Kenneth Branagh's first 70mm shot movie. He used it again for Murder on the Orient Express (2017).

Writer and director Sir Kenneth Branagh knew early on that he wanted a lot of long takes that moved about the castle interiors. He also wanted to avoid the floating feel of Steadicam shots. So all of floors of the Elsinore sets were carefully reinforced and leveled so that camera dollies could move smoothly over them without the use of tracks.

Although the production went to great lengths to make the exterior of Blenheim Palace look wintry, they were blessed on one day with an actual blizzard. Writer and director Sir Kenneth Branagh scrambled to think of an exterior scene that could be shot quickly to take advantage of the real snow. He selected the scene where the sailors deliver Hamlet's letter to Horatio, since Nicholas Farrell could read his lines off the letter. Branagh pulled Farrell away from his lunch break, and they quickly shot the scene.

Choreographing the numerous intricate dolly shots in this movie required a high degree of coordination between the actors, actresses, and the crew. They sometimes rehearsed as much as three hours for a single set up. Adding to the difficulty were the numerous mirrors lining the set of the great hall. Each shot was carefully scrutinized in playback to make sure that no crew or equipment were reflected in the mirrors. At one point during rehearsals for the "To be or not to be" monologue, one of the dolly grips gave Kenneth Branagh a note about his pacing, to insure he completed his line before the dolly became visible.

The wintry exterior scenes were achieved with a combination of real snow and artificial snow made from a detergent solution. There was much debate between production designer Tim Harvey and the groundskeeper of Blenheim Palace as to whether the artificial snow would harm the hedges and other greenery on the palace grounds. Fortunately when the production was finished, the hedges were unharmed.

One of Robin Williams's earliest roles was in The World According to Garp (1982), which also featured Glenn Close, Jessica Tandy, and Amanda Plummer. Close played Gertrude in 1990's Hamlet (1990), opposite Mel Gibson. Jessica Tandy played Ophelia opposite John Gielgud's Hamlet. Amanda Plummer's father, Christopher Plummer, played the title role in Hamlet at Elsinore (1964).

The was the first British movie to be shot in 65mm since Sir David Lean's Ryan's Daughter (1970), in which Sir John Mills appeared, and was made in Ireland. In the interim, Far and Away (1992) (also shot in 65mm in Ireland) was a Hollywood production on-location.

The film marked the only on-screen Shakespearean role for either John Mills (Old Norway) or Richard Attenborough (The English Ambassador).

Many of the actors in this movie have worked with writer and director Sir Kenneth Branagh before this production. Examples include Richard Briers (Much Ado About Nothing (1993)), Sir Derek Jacobi (Dead Again (1991)), Robin Williams (Dead Again (1991)), and Brian Blessed (Henry V (1989)).

Cast members Sir Kenneth Branagh, Sir Derek Jacobi, and Gérard Depardieu have played Cyrano de Bergerac. As translated into English by Anthony Burgess, in the speech where Cyrano rattles off a list of possible insults to his nose, he includes "Oh that this too, too solid nose would melt", a parody of the "too, too sullied flesh" line from this play. (In the Brian Hooker translation of "Cyrano", which José Ferrer played on-stage and on film, the line is given as "Was this the nose that launched a thousand ships?", a parody of "Was this the face that launched a thousand ships", a line from Christopher Marlowe's "Doctor Faustus".)

This was the first film in which both John Mills (Old Norway) and Richard Attenborough (The English Ambassador) had appeared since Dunkirk (1958) 38 years earlier. However, Attenborough directed Mills in three films in the interim: Oh! What a Lovely War (1969), Young Winston (1972) and Gandhi (1982).

Michael Maloney (Laertes) previously played Rosencrantz in Hamlet (1990).

Nicholas Farrell (Horatio) previously played Hamlet in Shakespeare: The Animated Tales: Hamlet (1992).

In addition to remembering all of their lines during the many long takes, the cast often had to memorize their marks as well. Normally their marks would be indicated with pieces of tape or other visual references on the floor. But these would have been visible in the shots, and consequently could not be used.

Richard Briers (Polonius), Michael Maloney (Laertes) and Nicholas Farrell (Horatio) appeared in the director Kenneth Branagh's previous film A Midwinter's Tale (1995), which concerns an amateur production of "Hamlet". They played Joe Harper, Henry Wakefield and Tom Newman respectively.

John Mills (Old Norway) and Richard Attenborough (The English Ambassador) were offered the roles of the murderers in Richard III (1955), in which John Gielgud (Priam) played the Duke of Clarence. However, Mills believed that it would be stunt casting and Attenborough was unavailable.

Kate Winslet's role was previously played by Helena Bonham Carter. Winslet and Carter have also both played sister to Branagh's ex-wife, Emma Thompson, in Sense and Sensibility and Howard's End.

Laurence Olivier's 1948 film of Hamlet; which he too starred in and directed; featured Peter Cushing in the role of Osric, and featured a young Christopher Lee as an extra. This was the first of many of their film collaborations, most of which were horror films produced by Hammer Studios. One of these was The Curse of Frankenstein. Branagh's previous film was Frankenstein, in which he and Robert De Niro played Cushing and Lee's roles.

Derek Jacobi and Timothy Spall appear in this film along with Rosemary Harris. They appeared together again in The King's Speech, which featured her daughter, Jennifer Ehle. Spall's roles in both films (Rosencrantz, Winston Churchill) were also both played by Gary Oldman in Rosencrantz and Guildenstern Are Dead and The Darkest Hour.

Julie Christie, Kate Winslet, and Judi Dench were all nominated for Best Actress the following year, as was a previous Ophelia, Helena Bonham Carter. All four actresses lost to Helen Hunt.

To help Billy Crystal feel at ease with Shakespearean language, Kenneth Branagh first asked him to play their scene like a gangster movie, with Crystal imitating Joe Pesci and Branagh as Robert De Niro.

John Mills and Richard Attenborough previously appeared together in Dunkirk (1958). Kenneth Branagh appeared with his grandson, Will Attenborough, in Dunkirk (2017).

The character of Fortinbras (Rufus Sewell) is frequently cut from stage and film productions of Hamlet. One previous production that did include him, Hamlet at Elsinore (1964), featured Donald Sutherland in the role. Sewell and Sutherland appeared together in The Pillars of the Earth (2010). Julie Christie appeared with Sutherland in Don't Look Now (1973) and The Railway Station Man (1992). Gérard Depardieu appeared with him in 1900 (1976). Derek Jacobi also replaced Sutherland in Kenneth Branagh's previous film, Dead Again (1991).

Robin Williams and Billy Crystal appeared together the following year in Fathers' Day (1997), a remake of the French film The ComDads (1983) starring Gérard Depardieu.

Some pathologists conducted a study determining how long a person lasts before dying after being stabbed directly. A scene from this movie where Hamlet kills Polonius was also viewed as reference to their study. In the end, it was found that a person, after being stabbed directly, can only last long enough to utter four words. This means that Polonius' uttering of the words "O, I am slain" as he dies is medically possible.

When Ophelia sings the famous "And will a not come again..." speech, Kate Winslet is singing a tune composed by Patrick Doyle specifically for that scene. The melody occurs in the score in several of Ophelia's scenes, foreshadowing her madness and death.

Hamlet stabs Polonius five times when Polonius is behind the curtain and Hamlet mistakes him for Claudius.