Director Terry Gilliam first met Bruce Willis while casting his film The Fisher King (1991). He was impressed by the sensitivity shown by Willis in the scene from Die Hard (1988) where McClane (Willis) talks about his wife while pulling glass from his feet. Talking to Willis, Gilliam discovered that this part was ad-libbed by Willis. Gilliam remembered this, and was convinced to cast him in this film.
Terry Gilliam gave Bruce Willis a list of "Willis acting clichés" not to be used during the film, including the "steely blue eyes look".
Features a fresnel (flat) lens, as did Brazil (1985), also directed by Terry Gilliam.
Director Terry Gilliam and producer Charles Roven had several arguments about how the film should end. Gilliam wanted to finish on the shot of Railly looking at young Cole while Roven preferred the scripted final scene in the parking lot outside the airport. In an attempt to dissuade Roven, Gilliam proposed an immensely complex setup involving two cranes on top of one another and a vast sea of cars in the hope that Roven would veto it as being too expensive. Roven not only okayed the shot but Gilliam so loved the result that he used it to end the film.
The scenes in the insane asylum were shot in Eastern State Penitentiary, a now-unused prison in Philadelphia.
In a scene where Cole is drawing blood from himself, the shadow of a hamster in a hamster wheel can be seen on the wall. This scene would normally be shot in 5 minutes, but took a whole day because the hamster would not move, and Gilliam is such a perfectionist that he insisted that even this detail should work as intended. For the rest of the production Gilliam's perfectionism was nick-named "the Hamster Factor".
A quick clip from The Andromeda Strain (1971) featuring a monkey in the throes of death, is seen on the dayroom television during a news report about the cruelty of using animal subjects in medical research.
The Army of the Twelve Monkeys is inspired by a passage in L. Frank Baum's novel, "The Magic of Oz", in which the Nome King and Kiki Aru convince twelve monkeys they will have an endless supply of food if they become human soldiers for them.
The voice of a reporter on the radio says, "This is Roger Pratt reporting." Roger Pratt was the film's director of photography.
Right after Dr. Leland Goines gets off the phone with Dr. Railly, Dr. Peters can be seen handling a tray of seven vials filled with a golden liquid. Twice in the movie, a passage of The Book of the Revelation is quoted referring to seven golden vials filled with God's wrath.
The revolver that Cole is handed at the end is a Cavalry Model Le Mat, as used by the Confederacy during the American Civil War.
Director Trademark: [Terry Gilliam] [bookends] begins and ends with young Cole's eyes.
Although this was inspired by Chris Marker's classic short, La jetée (1962), director Terry Gilliam had not seen it when this was made.
Toward the end of the film Cole and Railly are watching Vertigo (1958). The scene that is shown heavily influenced the film La jetée (1962) which inspired Twelve Monkeys. There is also a version of that same scene shown in La Jetée.
The two newscasters shown in the film were actual newscasters on Philadelphia's Channel 10 news at the time of filming.
Terry Gilliam was afraid that Brad Pitt wouldn't be able to pull off the nervous, rapid speech. He sent him to a speech coach but in the end he just took away Pitt's cigarettes, and Pitt played the part exactly as Gilliam wanted.
The Airport scene at the end of the movie was filmed at the Philadelphia Convention Center. However, the exterior shot of Cole and Dr. Railly walking into the airport was filmed at BWI Airport in Baltimore, MD.
Looking at the bodies in the aftermath of a fight Bruce Willis says, "All I see are dead people." Of course, "I see dead people" is the most famous line from 1999's The Sixth Sense (1999), which starred Bruce Willis.
Throughout the movie, actual monkeys appear on camera. From the "monkey and a roast beef sandwich" to zoo animals. Some people suggest 12 different monkeys appear in the film.
The final cut didn't do too well in the test screenings and so those involved discussed making major changes to the movie, but Terry Gilliam eventually decided to keep it as it was. When released it went on to make over five times its budget.
The "TV Ball" prop was notoriously problematic, with either the electronics or hydraulics breaking almost every time it was used.
Bruce Willis took a lower salary than his star-status would normally entitle, partly because of budget restrictions, but mostly because he wanted to work with Terry Gilliam. Actually Bruce did the movie for free. It was only after the movie was released that he was paid.
When James is escaping from the asylum, he runs past a security guard who is reading a tabloid, its cover is the now famous photo of the fictional "batboy" that was supposedly found in a cave in the 1990s. The story, about a society outcast ahead of his time, was made into an off-Broadway hit musical.
When Kathryn Railly first gets a call about Cole she is attending a poetry recital. The work being read is a quatrain from "The Rubaiyat" by Persian-born poet and astronomer Omar Khayyam. The quatrain being read is: Yesterday This Day's Madness did prepare; To-morrow's Silence, Triumph, or Despair: Drink! for you know not whence you came, nor why: Drink! for you know not why you go, nor where.
When Cole wakes up in the future to the doctors singing "Blueberry Hill," the painting above him is "Valley of the Yosemite", by Albert Bierstadt.
Artist Lebbeus Woods claimed that the interrogation chair in the movie closely resembled his 1987 illustration "Neomechanical Tower (Upper) Chamber" and managed to get a court to stop the movie 28 days after its release. He eventually settled with Universal for a six-figure sum.
In the 24 hour Hitchcock Theater, Katheryn transforms herself with a blonde wig. Hitchcock had a notorious obsession with blonde actresses in his films.
In the 24 hour Hitchcock Theater, Katheryn (Stowe) and James (Willis) are watching Vertigo (1958), then she transforms herself with a blonde wig and James saw her emerge within a red light. The scene perfectly match the scene where Kim Novak transforms herself as a blond and Scottie (Jimmy Stewart) saw her emerge within a green light. It can hear the same score written by Bernard Herrmann. Also Katherine wears the same coat as 'Kim Novak' wearing in the first part of Vertigo.
Director Terry Gilliam tried to persuade the studio to cast Nick Nolte as James Cole and Jeff Bridges as Jeffrey Goines, but was not successful as none of the two had any big hits since Another 48 Hrs. (1990) and The Fabulous Baker Boys (1989). Nolte and Bridges are in fact close friends, and have tried and failed to team up several times. Cutter's Way (1981) and Tequila Sunrise (1988) were both meant to star the pair. They finally worked together in Simpatico (1999).
A tagline originally suggested for this film was; "The future is in the hands of a man who has none." This was considered to be a confusing tagline, as it made it sound as though he had no hands, as opposed to having no future.