Factual error: After killing the random 'stray' old lady, Bateman flees the scene of the crime. When he triggers some car alarms, he walks past the Rector Street subway entrance. The sign for the station indicates it is served by both line 1 and 9, but line 9 was instituted in 1989, well after the year the movie is set in. (01:19:30)
Revealing mistake: As it often happens, much of this NY-set movie was filmed in Canada. Patrick Bateman's office building is actually part of the Toronto-Dominion Centre. A funny nod to this gimmick occurs after Patrick kills the janitor and has to sprint between building towers. While he runs in the long shot, a Canadian flag can be seen waving in the wind on the left side. (01:21:10)
Continuity mistake: When Jean goes through Patrick's belongings after his maniacal call, she gets one diary in each hand - but you may notice that they switch hands in the next shot. She grabs the P.B. one with her left hand in close-up but pulls it out with her right. (01:29:45)
Factual error: When Jean starts browsing Patrick's planner, the planner does not match any possible year the movie could be set in. For instance, in the 80s, October 8th was on a Friday only in 1982, way too early for the movie. Since the movie was shot in 1999 and the pattern of the days would fit, it's obvious that they simply bought a diary the day of the shooting or something like that. (01:30:05)
Continuity mistake: At the restaurant, Patrick approaches his lawyer to talk about the answer machine message he left him and the lawyer puts an unlit cigarette between his lips. The cigarette is already lit in the next shot when he mistakes Patrick for another colleague. (01:31:16)
Continuity mistake: When Bateman's lawyer does not recognize him, thinking he is a 'Davis', and brushes him off for the first time to try and go greet someone else ("Is that Edward Towers?"), a guy passes by them twice in two separate shots. (01:31:35)
Other mistake: When Jean looks at Patrick's increasingly twisted designs, it turns out that he drew a woman with a chainsaw stuck in her back on November 13th. That does not appear to make sense by the most basic movie inner logic (even if we discount any real-life reference to the year), considering he murdered Paul on December 20th and his descent into madness isn't supposed to be a slow one. (01:34:00)
Suggested correction: Just because he doodled the chainsaw on a specific date doesn't mean he killed her on that date.
It would have been quite strange if he just happened to draw a prediction of the murder months earlier, and it wouldn't make sense that he would keep a normal diary until September, then go crazy for months after but keep doodling in November of an old diary that he should have already filled (the movie is supposed to be well into the new year) but only from a certain point and in a crescendo. Julia... ahem, Jean didn't just find a scrapbook of insanity; she found the diary of his increasing spiral into insanity.
Factual error: When at the end of the movie there is a close-up on the TV where the yuppies are watching Ronald Reagan's address to the nation from August 12, 1987, it's a Sony KV-20M10, a model first introduced in 1994, therefore years after the movie setting. (01:34:40)
Visible crew/equipment: In the office scene when Kimball is talking with Bateman, a microphone boom can be seen in the CD's reflection behind Bateman.
Continuity mistake: When Bateman goes crazy and flees into his office, his hair is very messed up. However just after he sings and goes to his office, it is quite obvious his hair has been redone and gelled again.
