Continuity mistake: In the scene where Rocky and Nick are talking in the bathroom you can see Nick's back in the mirror - he has two nasty looking scratched up areas of bare skin on his back - then when he turns and returns to the bedroom you can see that he now only has a couple of superficial marks.
Continuity mistake: Michael Douglas waits in the dark in Jeanne Tripplehorn's apartment and says to her after she walks in, " Tell me about Catherine". At first we see a couch and chair on the right side of the room but two shots later as he walks towards her these two items have been removed from the room. (01:38:40)
Continuity mistake: When Nick and Gus are driving Katherine to the police station for the first time, they drive past the same stretch of coast about three times throughout the scene. Most obviously seen by the position of the small island - it jumps from being in the distance, to being even with the car, then behind the car, then in front again etc.