Revealing mistake: During the Miss United States Pageant, there are close-up shots of the audience and it is very obvious that in the balcony and back part of the audience, especially when seeing the 'men' with bow ties, they are fake - mostly cardboard cut outs. (01:22:50)
Factual error: In the beginning, Leonard looks at a copy of John G/Teddy's driver's license. The expiration date is listed as 2-29-01, but of course, 2001 was not a leap year, so there would've only been 28 days in the month. (00:12:45)
Other mistake: 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).
Continuity mistake: In the scene where Alex is watching the TV on how the plane exploded, look at the illustration shown. Then compare it with the illustration that appears on Alex's computer screen. The positions of the explosions shown are different. (00:50:42)
Continuity mistake: Before Sidney pulls the killer out of the door on the house set, we see the bedside table is lengthwise against the wall. As the killer falls towards the bed it's turns 90 degrees, so the bed is a bit closer to the door. (01:05:45)
Continuity mistake: When Claire first sees the ghost, Norman rushes in and Claire grabs and hugs him. Her hand was just in the tub yet as she's hugging Norman, her hand is dry. She would have left some kind of a wet mark on Norman's shirt.
Continuity mistake: When Shuya finds Utsumi dead, the proximity of her head to the girl behind her changes between shots, as does the position of her tie and gun beside her.
Continuity mistake: In the gas station scene after Ellen learns that Phil has drowned, she is so distraught she forgets to put the gas cap on and we can see it on the roof of her car as she drives away. But when she arrives at the police station we can see that the gas cap is on. (01:10:20)
Continuity mistake: At the club when Katie Holmes is sitting with her fiancé, she is wearing a black strappy dress with a strap hanging off her shoulders. She stands up to go and dance with her father and in the next frame the strap is in place on her shoulder.
Continuity mistake: After Willis rescues the people, he's at breakfast with his son and wife. He slides the newspaper to his son. Close-up on paper (beside orange juice) shows "Bold" typestyle on story slug. Camera pans up to Willis, cuts to son, cut back to newspaper. Suddenly typestyle is italicised (noticeable on "f" in "found"). (01:34:30)