Continuity mistake: The gatekeeper lets Marisa and David in; the position of his clipboard changes between shots, and so does the position of the other hand, quite more noticeably so since it's off the button column, then on it suddenly again. (01:17:50)
Continuity mistake: The guy that lies dead next to the crushed car at the party has his head tucked more or less closely under the right arm depending on the camera angle. (01:17:55)
Continuity mistake: When David opens the manhole to get in the sewers for the last time for the big finale, he is wearing the same blue sneakers he was wearing at the hospital, but as he goes down the ladder he is wearing black boots. (01:19:10)
Continuity mistake: When David confronts "Ramon", at first he shoots the beast (somehow hurting him more than anyone could do throughout the whole movie, even Kelly who practically shot him in the mouth) a few times, gun in the right hand, flashlight in the left hand. He runs then away, gun in the left, flashlight in the right. They swap again later. (01:20:00)
Continuity mistake: When Marisa tries to save the hero by telling an old lady to move her car, the window is all the way down looking in, an inch raised looking out. (01:23:05)