Looking for a way to create the character of Patrick Bateman, Christian Bale stumbled onto a Tom Cruise appearance on David Letterman. According to American Psycho (2000) director Mary Harron, Bale saw in Cruise "this very intense friendliness with nothing behind the eyes" and Bale subsequently based the character of Bateman on that. Interestingly, Tom Cruise is actually featured in the novel; he lives in the same apartment complex as Bateman, who meets him in a lift and gets the name of Cocktail (1988) wrong, calling it "Bartender".
In each scene with Detective Donald Kimball (Willem Dafoe), Mary Harron asked Defoe to portray his character three different ways: 1) Kimble knew Patrick Bateman killed Paul Allen, 2) Kimball didn't know Bateman killed Allen, and 3) Kimball wasn't sure if Bateman killed Allen. Harron would then edit the takes together, giving the audience an unsure vibe of what Detective Kimball thought of Bateman.
During the shooting of the film, Christian Bale spoke in an American accent off set at all times. At the wrap party, when he began to speak in his own British accent, many of the crew thought he was speaking that way as an accent for another film - they had thought he was American throughout the entire shoot.
To block the three-way sex scene with two prostitutes, Mary Harron and Christian Bale watched x-rated tapes. In her commentary, Harron says Bale made stick-figure drawings of the positions he thought would work best.
Two scenes featured unexpected improvisation by Christian Bale. When Bateman is jumping rope, he starts to skip and cross his jump rope as a schoolgirl would. Bale surprised director Mary Harron even more by starting to dance as Bateman was preparing to kill Paul Allen (Jared Leto). That time, she says in interviews and the commentary, she collapsed with laughter.
The film had various problems with designer labels during production. Cerruti agreed to allow Christian Bale to wear their clothes, but not when the character was killing anyone; Rolex agreed that anyone in the film could wear their watches except Bateman (hence the famous line from the book "Don't touch the Rolex" had to be changed to "Don't touch the watch"); Perry Ellis provided underwear at the last minute after Calvin Klein pulled out of the project; Comme des Garçons refused to allow one of their overnight bags to be used to carry a corpse, so Jean Paul Gaultier was used instead.
When Leonardo DiCaprio was still attached to the project, feminist activist Gloria Steinem lobbied him not to make the film, as his fan base consisted predominately of young teenage girls, and he could ruin his career. Steinem had spoken out about the novel several times and was against the film version in any incarnation. Her involvement is rendered especially interesting insofar as she would soon become Christian Bale's stepmother.
When Lions Gate picked up the rights for the film, Mary Harron was set to write and direct. Initially, she considered various actors for the role of Patrick Bateman, including Billy Crudup (who was offered the part but turned it down), Ben Chaplin, Robert Sean Leonard, Johnathon Schaech, Jonny Lee Miller, and Jared Leto. Eventually, Harron offered the part to Christian Bale, who accepted. The producers tried to talk Harron into casting Edward Norton, but she refused, and was ultimately allowed to cast Bale, but only on the proviso that she cast at least two other big name actors in supporting roles. To this end, Harron hired Willem Dafoe to play Kimball and Reese Witherspoon to play Evelyn. However, after they had agreed to appear, Lions Gate told Harron they were going to make an offer to Leonardo DiCaprio to play Bateman. Harron told them if they did, she would leave the project, which is exactly what happened. Oliver Stone was subsequently hired to replace Harron, working from a script by Matt Markwalder. Stone was set to cast James Woods as Kimball, Cameron Diaz as Evelyn, Elizabeth Berkley as Courtney and Chloë Sevigny as Jean. Stone also decided to keep Leto on the project as Paul Allen. However, DiCaprio left the project to shoot The Beach (2000) instead, and as the budget began to get out of control, Stone also left, prompting Lions Gate to rehire Harron, who returned to her original castings decisions, and decided to keep Sevigny on the project.
While the novel "American Psycho" is set in 1989, the film adaptation is set in 1987. This is evidenced by the scene where Patrick is briefly reading Zagat's Survey: 1987. Also, the televised speech by President Ronald Reagan, as shown the final scene of the film, also occurred in 1987 (whereas Reagan had already left the White House by the time the events in the original novel took place).
Initially given an NC-17 rating by the MPAA, the cinematic kiss of death due to distribution difficulties. Mary Harron argued volubly against the rating but was forced to make some minor trims to receive an R rating.
The scene in which Patrick Bateman yells at the Asian woman at the laundromat was filmed at a small cleaners on Jarvis street in Toronto, Canada. Much of the building scenes (his escape near the finale for example) was filmed in the financial district downtown.
After the novel was originally optioned in 1991, author Bret Easton Ellis himself was set to write the script for director Stuart Gordon with Johnny Depp starring as Patrick Bateman. Gordon wanted to do the film in black and white and stick as close to the book as possible, meaning a guaranteed X-rating. After the project fell through, David Cronenberg replaced Gordon, with Brad Pitt set to star. This project also failed to get off the ground.
This was the second time in two years that the film's distributor Lions Gate found itself in trouble with the MPAA over one of their films. In 1999, they had run afoul of the censors with Dogma (1999) which was deemed to be blasphemous.
The Huey Lewis and the News song "Hip to Be Square", which appears in the film, was initially on the soundtrack album, but it was removed shortly after release because of a lack of publishing rights. The album was recalled and reissued without the song, although some versions of the initial batch had already sold. Over the years, this incident has developed into the myth that Huey Lewis himself refused to allow the song on the album due to the content of the movie.
At one point, the novel was considered for the possibility of a TV show on NBC, starring Kevin Dillon. However due to ownership, the film was eventually made. This was later squeezed into an in joke on Entourage (2004), starring Kevin Dillon.
In the final scene, Patrick Bateman uses the phrase "Rockin' and Rollin' and whatever..." This is a phrase often used by Sean Bateman, Patrick's younger brother, in the book 'The Rules of Attraction', also written by Bret Easton Ellis. Sean also makes a short appearance in the novel 'American Psycho', where he also uses the phrase.
The scene in which Patrick and Courtney are in bed (when she asks him if he'll call her before Easter) is taken from Ellis' first novel "Less Than Zero". The conversation between Clay and Blair in that novel is almost identical to the one in the film (Easter has been substituted for Christmas). Although in the book "American Psycho", Courtney (while lying in bed) does ask Patrick if he will call her before thanksgiving.
In the scene with the prostitute Christie (Cara Seymour), Bateman's friend mentions their mutual acquaintance "Alison Poole". Alison Poole is the narrator and main character of the novel 'Story of My Life' by Jay McInerney, a contemporaneous peer author to Bret Easton Ellis.