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.
Visible crew/equipment: In the scene where Patrick Bateman is walking the streets, just before that encounter with the lady who is waiting for the red light to change, you can see the camera crew reflected on the store windows.
Continuity mistake: In the scene where Patrick is in his office working on a crossword puzzle before talking to Jean, he is writing with his right hand. When the shot changes to the reflection of Patrick's glasses, the reflection shown is as if he is using his left hand. The reflection isn't a mirror image as it should be.
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.
Answer: There are two possible answers. First, Carnes doesn't recognize Christian Bale as Bateman, instead thinking he is someone named Davis. He insults Bateman and thinks "Davis" left the message as a joke. Realize also that someone claims to have seen Owen/Allen in London, but mistook Herbert Ainsworth for him. Second, Bateman is delusional and only thinks he killed Owen/Allen, who is in fact alive and in London.
Greg Dwyer