I just realised why the main character's name is significant. Patrick Bate man.
Bateman's lengthy descriptions of the outfits that people wear have a slightly sinister hidden purpose. After a bit, the reader stops bothering to read every little detail about how "Hamlin is wearing a suit by Lubiam, a great looking striped spread-collar cotton shirt from Burberry, a silk tie by Resikeio and a belt from Ralph Lauren," which occurs nearly every chapter. This causes the reader, much like the yuppies themselves, to not pay that close attention to what Bateman is saying, which can, in a few cases, much like his "friends," cause the reader to miss something horrific that Bateman might say mid narration, while simultaneously showing how the reader, who is supposedly actively "listening" to what Bateman has to say, begins to treat what he has to say about things with the same lack of care that the yuppies do.
Word of God said that he very deliberately chose what outfits that he was describing in any given scene, so that if you actually look up the clothing products, you'd realize how clownish and stupid they look together.
Related to the clothes as well - almost every time the narrator, in a single scene, praises someone's clothes (usually his own) and ridicules someone else's clothes, the two people being talked about are wearing almost identical outfits- but from different brands!
In the movie, Patrick's business card is colored "bone". Patrick's a Serial Killer.
The Wall Street firm Bateman works for is called Pierce & Pierce, also the name of the firm Sherman McCoy works for in The Bonfire of the Vanities.
The first time I saw the movie, I was trying to figure out what the artworks in Patrick's apartment were supposed to be depicting. (the black and white art print of the man in the suit) At first I thought the man was supposed to be falling but with the pose, I realized the pose suggested he is being attacked, with his arm held up defensively. Can also count as Foreshadowing if you notice it before Paul Allen gets axed in Bateman's apartment.