Samuel L. Jackson said of working with James McAvoy on the movie, "As good as I like to think I am or what I do and how I do it, watching somebody transform characters in front of your eyes and have an argument with four different people is pretty amazing."

James McAvoy based one of his 23 personalities on a young Saoirse Ronan, who he worked with on Atonement (2007).

Although Disney owns the rights to Unbreakable (2000), director M. Night Shyamalan retained the rights to any potential sequels, so that the studio could not make one without his involvement. Such was his desire for creative control that he co-financed Glass (2019) by mortgaging his house.

Director M. Night Shyamalan talked about the importance of colors in this movie, saying, "I chose green for David Dunn because psychologically, it is associated with life giving properties. David is the protector of life. I chose ochre or mustard for The Beast because this color is associated with religious ceremonies, Hindu and Buddhist. A monk's robe. I see The Beast as an evangelist, a preacher who wants to help save 'The Broken.' Finally, I chose purple for Mr. Glass because this color has been associated with royalty, majestic qualities. Elijah sees himself as important, a main character of comics."

Samuel L. Jackson, who played Elijah, is five years older than Charlayne Woodard, who played Elijah's mother.

The hospital where the movie was filmed was a former mental hospital in Allentown, Pennsylvania.

While promoting the movie at the 2018 Comic-Con, writer and director M. Night Shyamalan noted that the film was "a once-in-a-lifetime movie in that Disney arm Buena Vista International, which owns the rights to Unbreakable (2000), and Split (2016) studio Universal Pictures, agreed to team for the film." He continued saying, "I don't think this will ever happen again, where two studios had two IPs they completely owned, and I said, 'Can we make a sequel to both, and you guys share it?' and they said 'Yes.'"

Director M. Night Shyamalan said that the original cut of the film had a run time of nearly three and a half hours. He "trimmed it up a bit" by cutting three of Kevin Crumb's 23 personalties out of the film.

In one of the scenes inside Kevin Crumb's cell, several toothbrushes are visible on a shelf, indicating each of Kevin's personalities has its own toothbrush.

Director M. Night Shyamalan said, "As the characters believe in the comic book world, the primary colors in the film become more dominant. As they stop believing, they fade to a monochromatic world. The pink room where they do therapy is pink, red fading to white, because this is where they stop believing."

The original script for Unbreakable (2000) included Kevin as an emerging villain for David to face against, but director M. Night Shyamalan could never make it work within the confines of a single movie. Thus, Kevin ended up split off into his own movie, with this film as the culmination of the original idea.

Sarah Paulson accepted her part without reading the script, even though her role was originally written for a man, for the opportunity to work with director M. Night Shyamalan.

Bostin Christopher returns as the Comic Book Clerk from Mr. Glass' local store. He even uses similar dialogue to show that he is that very same character from Unbreakable.

The comic book store Dr. Ellie Staple visits near the end of the film is the same comic book store in which Elijah Price buys a comic in Unbreakable (2000).

Inside the comic shop Joseph visits, he walks past a neon purple "Villains" sign and a neon green "Heroes" sign. Mr. Glass' signature color is purple, and Dunn's signature color is green.

James McAvoy severely ups the ante on the number of personalities he portrays in a single film since the previous "Split" installment, from 9 to a whopping 20 personalities appearing on-screen.

Under normal circumstances, the film would have been a nightmare of red tape to pass through because Unbreakable (2000) and Split (2016) were produced by different studios. Instead, this was the first ever film co-production between Universal and Disney, which have been heated rivals in both the film and theme park businesses for more than half a century. Prior to this film, most Universal/Disney co-productions were relegated to television, most notably Monk (2002). Reportedly, Disney had no problem letting the film Split (2016) introduce David Dunn into its final scene, so long as they had some input on a full sequel.

This movie had a 39-day shoot that started on October 2, 2017, with a script comprising 134 pages.

While there was interest in creating a sequel to Unbreakable following its release, Touchstone Pictures opted not to finance one at that time despite the film's solid box office performance. Shyamalan set out on writing Split using a character he had written for Unbreakable but pulled from the script due to balance issues. Shyamalan realized the opportunity he had to create a trilogy of works, and adapted the ending of Split to establish the film as within the Unbreakable narrative. This included securing the rights to use Willis' Unbreakable character from Disney, with the promise of including them within the production and distribution of this third film alongside Universal Pictures should it be made. Split was a financial and critical success, and by April 2017, Shyamalan announced that he had started the production process for Glass.

The comic book theme was first introduced in Unbreakable (2000), and alliteration is frequently seen in the names of comic book characters (Peter Parker, Bruce Banner, et cetera). This movie follows this theme with superhero David Dunn.

Composer West Dylan Thordson used several Unbreakable (2000) themes that were written by composer James Newton Howard.

It took M. Night Shyamalan 19 years to make the trilogy, as the release date suggests (which is 2019). Unbreakable (2000) was being developed shortly after the success of The Sixth Sense (1999). Sixteen years later, Split (2016) came out, and shortly after it, this movie was announced.

This film marked the fifth time Bruce Willis and Samuel L. Jackson appeared in a movie together. The others were Loaded Weapon 1 (1993), Pulp Fiction (1994), Die Hard with a Vengeance (1995), and Unbreakable (2000).

There is a nod to both of the biggest comic book companies Marvel and DC in the film. The description of The Osaka Tower as 'A True Marvel' and on a news headline stating that the state of washington 'D.C. offers it's respect'. There is also an episode of The 60's Batman series shown in a comic book store scene.

This was the first M. Night Shyamalan film to be a co-production between two major film studios, Universal Pictures and Touchstone Pictures (the latter is one of the film studios owned by the Walt Disney Company). The film was also Shyamalan's first film with The Walt Disney Company since The Village (2004).

Director M. Night Shyamalan drew inspiration from the following comic books: "Saga," "Forbidden Brides of the Faceless Slaves in the Secret House of the Night of Dread Desire," "Sand Castle," "Paper Girls," "Daytripper," and "Last Look."

When Elijah Price/Mr. Glass sees David Dunn, his arch nemesis, has joined him in the same sanitarium, he cracks a small, menacing grin. This is similar to a scene in Frank Miller's acclaimed Batman: The Dark Knight Returns, Part 1 (2012), as an incarcerated, seemingly catatonic Joker breaks from his slumber with a sinister half-grin upon seeing Batman returning to Gotham City. In both scenarios, the villain regains their purpose and drive once their old enemy reappears.

According to Writer and Director M. Night Shyamalan, this movie is "the first truly grounded comic book movie."

Shyamalan psychologist: Where Unbreakable followed a man whose modest image of himself had blinded him to his true power; and Split explored the power of a monster created by a traumatized mind, Glass is interested in the very essence of identity by asking a question: are we objectively what we are, or rather the physical result of what our minds shape and determine? Are you a superhero if you think you are?

Every personality played by James McAvoy had to have a distinct voice and presence. McAvoy therefore worked with director M. Night Shyamalan to define each identity.

This was the second M. Night Shyamalan movie to be released in IMAX. The first was After Earth (2013).

This is the third movie where James McAvoy had to shave his head, after X-Men: Apocalypse (2016) and Split (2016).

This was M. Night Shyamalan's thirteenth directorial feature.

The film was a proper sequel to Unbreakable (2000) and was released nineteen years later.

This movie was announced on April 16, 2017, shortly after Split (2016) was out of the theaters.

Writer and Director M. Night Shyamalan set the release date at January 18, 2019, when he announced this movie.

Leslie Stefanson's first acting role in 16 years.

The movie repeatedly and prominently references a fictional "tallest building in Philadelphia," the so-called Osaka Tower, which evokes (and could intentionally be a reference to) the equally fictional Nakatomi Plaza, the site of Bruce Willis' action debut, "Die Hard."

Many cast members have previously starred in other superhero/comic book movies. Bruce Willis starred in Sin City (2005), Red (2010), Red 2 (2013) and Sin City: A Dame to Kill For (2014), Spencer Treat Clark in Agents of S.H.I.E.L.D. (2013), James McAvoy in Wanted (2008) and the X-Men film franchise, Samuel L. Jackson as Nick Fury in the Marvel Cinematic Universe, and as Octopus in The Spirit (2008), Anya Taylor Joy in New Mutants (2019), and Sarah Paulson in The Spirit (2008).

This is to be the first movie released under Disney's Touchstone Pictures label since Strange Magic (2015) not to be a motion picture released under the DreamWorks Pictures deal from 2011 to 2016.

The movie was announced via director M. Night Shyamalan's Twitter account on April 26, 2017.

"X-Men" comics are visible in the comic book store scenes. James McAvoy played the younger version of Charles Xavier/Professor X in the "X-Men" films.

"Split" and "Glass" are each eleven minutes longer than their previous entries. "Split" is 117 minutes long while "Unbreakable" is 106 minutes long. "Glass" is 128 minutes long while "Split" is 117 minutes long.

In the film, the Osaka tower is across the street from Philadelphia's 30th Street station and can be seen a relatively short distance away from the front steps of the hospital. In reality, the hospital used for filming (Allentown State Hospital, 1600 Hanover Ave., Allentown, PA) is not only facing the wrong way, but actually 46 miles from 30th Street station, and so downtown Philadelphia would not be visible from the hospital.

James McAvoy's character previously appeared in Split (2016), which was distributed by Universal, and now this film, which is partially distributed by Disney. This made his character the second to cross over between the two studios. The other character is Bruce Banner/Hulk, who appeared in The Avengers (2012), along with Samuel L. Jackson.

One of the hallmarks of M. Night Shyamalan's films is the seamless integration of visual effects into a real world. Unlike almost every other great studio movie - and certainly every superhero movie - its effects never draw attention to them. In appearance, it is often impossible to say which elements, if any, are computer generated. This is explained both by a pure creative will and by practical considerations.

Many Marvel comics are on display in the comic book store scenes. Samuel L. Jackson is also known to audiences as Nick Fury in the Marvel Cinematic Universe.

Elijah Price calls himself: "Mr. Glass". He wears a large bejeweled tie pin with the initials: "MG".

Despite playing his character's mother, Charlayne Woodard is actually five years younger than Samuel L. Jackson.

Bruce Willis and Sarah Paulson appeared in the Ocean's film franchise. Bruce had a cameo in Ocean's Twelve (2004), and Sarah was in Ocean's Eight (2018).

Principal photography on the film began on October 2, 2017 in Philadelphia, following a week of rehearsals. Director M. Night Shyamalan planned for a 39-day shoot in this period. On October 31, 2017 it was reported that Shyamalan was filming at the Allentown State Hospital for the film and would be filming there for a few weeks. On December 12, 2017, Shyamalan revealed that four scenes were being planned to be shot in January 2018, stating he would have to travel for those. On February 16, 2018, a scene was filmed at Bryn Mawr College in the athletic center.

Takes place three years after the events in Split.

When Dr Staple is in the comic book store, an episode of the 1966 "Batman" TV series is playing on the television. The episode is season 1, episode 3, "Fine Feathered Finks" featuring the first appearance of Burgess Meredith as the Penguin. It's also significant in that this is the 3rd episode of the TV series and the film "Glass" is the third film of M Night Shyamalan's shared universe series.

This is the 5th movie with both Samuel L. Jackson and Bruce Willis starring. They are Loaded Weapon (1993), Pulp Fiction (1994), Die Hard With a Vengeance (1995), Unbreakable (2000), and Glass (2019)

While discussing comic books' history, excited comic book clerk shouts "Booyah"! - a catchphrase by a DC superhero Cyborg.

M. Night Shyamalan: the customer at the Dunn Security store who recognizes David Dunn as a former security guard at the stadium and credits Dunn for putting him on a good path.

Director M. Night Shyamalan was able to incorporate unseen footage from Unbreakable (2000) into this film, for scenes depicting the memories of David Dunn or Joseph.

Towards the end of the movie, it is revealed that Elijah (Samuel L. Jackson) was also responsible for the death of Kevin's (James McAvoy) father, an event that ultimately forced Kevin to stay with his abusive mother, a situation which caused Kevin to form his multiple personalities. In the movie; Unbreakable, David (Bruce Willis) bumps a woman holding a boy's hand at the stadium. This bump triggers a reaction in David, helping him hear the scream of the boy (possibly Kevin) who was being abused.

In Unbreakable, Elijah explains that David's unusual weakness to water is actually a hero's trait after reading a comic book about a secret society that monitors the weaknesses of various good and evil super humans in order to stop them. Therefore it's very likely that Elijah noticed the similarities with Dr. Staple and her organization and had her true intentions figured out the moment he met her.

In the end of the movie when Ms. Price, Casey, and Joseph are at the train station they are wearing the colors that match their hero/villain's respective color; Casey is wearing a yellow top and Kevin's color throughout the film was yellow, Ms. Price is wearing purple which is Elijah's color throughout the film, and Joseph is wearing a green jacket which was David's color throughout the film.

When Casey (Anya Taylor-Joy) is doing her comic book research she asks the teller about its history. He points out Action Comics #1 whose cover classically portrays Superman holding a motor vehicle over his head, shaking the crooks out of it. In this film, Mr. Glass (Samuel L. Jackson) refers to the finale as not a Limited Edition, but an "origin story" before his demise. We then learn his master plan was to kickstart the real world comic book universe himself. And thus the final image of the film is the masses at the train station watching The Beast (James McAvoy) lifting a police car up to remove the cops therein. The same image that kicked off the world of comics so too reveals the "Unbreakable" universe to the "real" world.

Samuel L. Jackson does not speak until about an hour into the movie.

When Joseph Dunn is about to leave the comic store, he turns around and looks at the villain section and the comic book "Whisperman" catches his eye. The comic features a villain puppet master and the sub print asks "Who are his parents?". This comic is a hint at Dr. Ellie Staple (Sarah Paulson) being the real villain in the film. Dr. Staple (which was originally written as a male role) is a master in the art of deception and is obsessed with her ability to convince others of any reality she deems necessary.

Mr. Glass (Samuel L. Jackson) threatens to blow a few stories off of the brand new Osaka tower with The Beast (James McAvoy) as his right hand. He uses this to influence David Dunn to break free to stop them. This is a classic super villain trope of a veiled master plan. Similarly Lex Luthor (Gene Hackman) fibs about a poison gas pellet he plans on releasing to the public in order to lure Superman (Christopher Reeve) to his hideout in Richard Donner's "Superman: The Movie".

Despite having superhero and supervillian monickers, David and Elijah refer to each other by their Christian names. This is common amongst comic book rivalries such as Charles Xavier and Erik Lehnsher, as well as Reed Richards and Victor Von Doom, for example. Though Mr. Glass finally calls David by his superhero name, Overseer, when he taunts him to finally break free of his cell and to come and stop he and The Beast.

The line, "The classic turn! The enemy becomes the ally!" has more meaning when spoken by Glass than apparent at first. Events unfold so that Glass does seem to become the hero instead of the villain.

On the cover of the magazine, the headline calls the Osaka tower "A Real Marvel." This is a reference to the movie's premise that real people are the basis for comic book characters, of which Marvel comics is one of the largest.

In this movie, water is a weakness for David Dunn. In Signs (2002), another movie by M. Night Shyamalan, water is a fatal weakness of the invading aliens.

Dr Staple's role is hinted at by her name. She gathers comic-book heroes and villains together, and tries to be a master manipulator of their paths. The pages of a comic book issue are held together with staples, which keep the narrative in the right sequence.

At the end of the movie, Dr. Ellie Staple Sarah Paulson tells Mr. Glass Samuel L. Jackson that 'There just can't be gods among us". "Gods Among Us" is the subtitle of the DC Comics fight game Injustice: Gods Among Us (2013).

Dr. Staple, at the end of the movie, says to Elijah/Mr. Glass that, "there just can't be Gods amongst us". As she sets out stopping those with supernatural abilities. This could be a direct correlation between this movie (Glass) and another movie (Jumper) in which Samuel Jackson plays a villain who sets out on a task very similar to Dr. Staple to stop supernatural beings. As Jackson's character Roland in Jumper states almost the same words that Dr. Staple does, "Only God should have this power."

In this movie, Elijah labels the climactic scene as the collection of main characters. This could be a nod to his character, Nick Fury's responsibility for bringing together all MCU characters together in the Avengers movies.

In the background during two of the scenes in the comic book shops, one of the comic book titles is "Strange Happenings" which is similar to M. Night Shyamalan's earlier movie "The Happening"