Continuity mistake: Near the end of the film when Tyler throws Ed Norton down the steps we get the view from a security camera, however we can see the camera we are supposed to be looking through in the top right hand corner. (02:09:10)
Revealing mistake: Before the final fight scene between Tyler and the narrator, Edward Norton points a gun at Tyler telling him to step away from the van. Tyler breaks the key and throws it away. When this shot is seen through the security footage, then in the far left security computer screen we can see that there is already a gun shot hole in the back window of the van, and there is also some random guy walking in the top left corner of the screen. (02:07:35)
Continuity mistake: When they are preparing to confront the City Councilman, Brad Pitt's character pulls him in to the bathroom. If you really look at the locks on the door you see that as he is pulling him in there is no deadbolt lock, but when the Councilman is halfway in through the mirror you can see that the same door has a deadbolt lock. (01:33:45)
Continuity mistake: When Tyler Durden goes to Marla's apartment to prevent her suicide, he removes a cigarette from his mouth and gestures as if he is throwing it down on the floor at the top of the stairs. Then the cigarette is back in his mouth when he proceeds to the door, at which point he really does throw it down on the floor. (00:50:30)
Continuity mistake: When the narrator first meets Bob, Bob starts telling him how he used steroids. In one shot we see the narrator's right hand is resting at the middle of Bob's back, but in the next shot we see his right hand at the top of Bob's back and a little above his armpit. (00:08:10)
Continuity mistake: At the end of the film, when Ed and Brad are fighting in the parking garage, as Brad punches and throws Ed around like a rag doll, Ed's face goes back and forth between being caked in blood and being clean from shot to shot.