American Psycho (2000)

Visible crew/equipment: In the scene after Patrick Bateman's second encounter with the detective in his office, we see Bateman having sex at Courtney's apartment. After he rolls off her, Bateman approaches the large, stand-up mirror in the bedroom.  In the upper right hand corner of the mirror, a boom microphone can clearly be seen moving around to pick up Christian Bale's lines. The next time we get the same long shot, the microphone is gone.

Other: Several close-ups of the business cards of Patrick Bateman and his associates reveal a misspelling of the word "Acquisitions" (the "c" is missing - not a small error, given that this is the name of their department).

Character mistake: Patrick, being the music buff that he is, mistakenly claims that Huey Lewis' Fore! came out in 1987, when it was actually released in 1986.

When Bateman in the end of the movie confesses his murders to the answering machine, he mentions murders like a man with a dog and a girl with a nail gun. Those are all murders described very graphically in the book.

Willem Dafoe was asked to play Donald Kimball in 3 different ways: he thought Bateman was guilty, he didn't think Bateman was guilty, and he wasn't sure if Bateman was guilty. They were all blended together to make the audience not know what Kimball thought of Patrick Bateman.

Leonardo DiCaprio was originally tapped to play the role of Patrick Bateman, however his agents felt that the role was to twisted and may hurt his image with his younger fans. He ended up passing on the role.