Factual error: The phone by Patrick's bed is the BeoCom 1401 from Bang and Olufsen, a model introduced in 1991, well after the movie events. (00:05:00)
Factual error: In the opening club scene, the main song played is "True Faith" by New Order. The early part of the movie takes place in 1986, and the song was released in late July 1987. (00:03:45)






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