Factual error: When Nick is looking up information about Hazel, the computer says she was released from San Quentin. That's a men's only prison.
Character mistake: When we see the door to Elisabeth's, her name is spelled with a s. Later when Nick looks her up on the computer, it's spelled Elizabeth.
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.