When Bateman is using the pay phone on Park Avenue, the skyscraper in the background says "Met Life", when it should say "Pan Am". Although the building was sold by Pan Am to Met Life in the 1980s, the name displayed on the building wasn't changed until the early 1990s.
Early in the movie, Bateman comments that he is listening to the new Robert Palmer album. The song that's heard during this scene is "Simply Irresistible", which was on his album Heavy Nova, which came out in November 1988.. But the Ronald Reagan speech seen at the end of the movie occurred in early 1987, not 1988.
In one scene Bateman says "Hasta la vista, baby", a quote made famous by Arnold Schwarzenegger in Terminator 2: Judgment Day, a movie not released until 1991. This movie takes place in 1987. (The term was however used in the 1987 Jody Watley song 'Looking for a New Love' which may have been where Bateman was quoting from.)
As Jean is leaving Patrick's apartment, she reminds Patrick of his lunch appointment the following day, but the second-half of Jean's line appears to have been dubbed. It is unclear what the actress was actually saying.
Patrick attributes the quote, "When I see a pretty girl walking down the street, I think two things. One part wants me to take her out, talk to her, be real nice and sweet and treat her right. The other part just thinks what her head would look like on a stick", to Ed Gein. However, it was actually Ed Kemper.
Whitney Houston's 1985 debut album entitled "Whitney Houston", contains three number one singles, not four as stated by Patrick when Christie and Elizabeth are making out. Whitney Houston's second album entitled "Whitney", contains four number one singles and was released in 1987.
The album Bateman holds up while entertaining the escorts is Phil Collins' solo album "No Jacket Required", although "In Too Deep" is from the Genesis album "Invisible Touch". Although it seems like a minor error, someone as obsessed with pop music as Bateman is would be unlikely to make such a mistake.
When being questioned by Detective Kimball, Patrick states on the night of Paul Allen's murder, he was at dinner with a woman named "Veronica". Later, however, when he and Kimball are at lunch, he says he must have had dinner with "Victoria" the following night. He changed the name of the woman. While it is possible Patrick got mixed up, it is unlikely a man of his organization would do such a thing when faced in such a situation.
During Patrick Bateman's first meeting with Detective Donald Kimball, Jean brings Detective Kimball mineral water that he does not want. She sets the bottle of water and glass on the corner of the desk. During the conversation between Bateman and Kimball, the glass and bottle move from the corner of Bateman's desk to a slightly deeper part of the corner, and an ashtray moves into their original place.
(possibly deliberate errors by the filmmakers): In one of the last scenes where Patrick enters a bar/restaurant, a door to his left has a sign on it saying 'NO EXIT'. However, in the last scene where Patrick is sat down and takes a drink from his glass the door behind him now reads 'THIS IS NOT AN EXIT'.
In the scene where Patrick is sitting on his couch making reservations for Dorsia, the camera angle from the side shows his hair styled entirely back from his face. When the camera angle switches to the front there is a noticeable lock of hair hanging in front of his face. The camera switches back to the side view and his hair is styled entirely back from his face again.
When Patrick Bateman murders Paul Allen, the collar on his raincoat changes from being folded on both sides, to one side raised, to half the collar up back to folded on both sides. This alternates between many shots.
When Patrick and Evelyn arrive at Espace, Vandon and Stash are sitting next to Bryce and Carruthers when being introduced to Patrick. Later in the conversation, they are sitting on the opposite side of the table.
During Patrick's killing spree towards the end of the movie, when he is running between the two nearly-identical buildings, a Canadian flag is intermittently visible flapping out from behind the building on the left, revealing that this scene was shot in the Toronto-Dominion Plaza, not in New York.
While rhapsodising about Genesis' "Invisible Touch" LP, Bateman states that "Phil Collins addresses the problems of abusive political authority" on the song "Land Of Confusion." That song's lyrics were written by the band's guitarist/bassist, Mike Rutherford. But all of the songwriting credits on that Genesis album were indiscriminately credited to all three Genesis band members (Banks, Collins, Rutherford), so Patrick wouldn't necessarily know who wrote the lyrics to which specific songs.
All of the windows show views of the cityscape with the horizontal line far above normal. This signals that the views are backdrops which are set too high. Often one looks up at a character and at the same time looks down on the streets, which is impossible.
The goof items below may give away important plot points.
When Bateman kills Paul Allen, two GQ magazines which can be seen on the table are from June and August 1987, respectively. But at the end of the film, quite some time later, there's a Ronald Reagan speech from March 1987 going "live" on TV.
Bateman could not have killed Jean with the nail gun because that model of nail gun must be plugged into an air compressor for the nails to be fired. If he had pulled the trigger the way he was holding it [without it plugged into anything], nothing would have happened.
When Bateman hits Paul Allen with the axe for the first time, the blood sprays on him before he actually hits him. Also the blood comes from a different angle than where Allen's head is supposed to be.