Continuity mistake: In the scene on the ferry, when Williams and Pacino are talking, in the shots showing Williams, Pacino is facing the center of the ferry frequently, while immediately afterward in the shots showing Pacino, he is facing Williams again.
Continuity mistake: When Dormer and Finch meet up after the interrogation, Dormer slams Fince against a metal support beam and the position of his hands of Finch change from being pressed against Finch's left cheek to being pressed against his neck/shoulder area as the camera angle changes. Happens about 3 times during scene.
Continuity mistake: When Robin Williams is being questioned by the police for the first time, one of the cops is talking to him. Very soon afterward the cop leaves the room and is walking away. We see the cop in the distance in another room, yet we hear the cop talking to Robin Williams again as Al Pacino shuts the door. Almost immediately, the camera angle changes to the cop as he finishes talking. He is standing in front of Robin Williams again.
Continuity mistake: When Al Pacino runs along the boardwalk towards the floating logs, following Robin Williams, in the shots showing him from behind he is running with his arms spread at a considerable angle, while in the shots showing him from the front, he is keeping his arms into his body. (00:25:20)
Factual error: Al Pacino is the subject of an internal affairs inquiry in Los Angeles. It's unlikely a police officer under investigation in L.A. would be sent to Alaska to work on a murder case. Police officers under investigation are routinely given desk assignments until officially cleared and allowed to return to active duty.
Continuity mistake: During the final fight, Pacino & Williams shoot it out in a small boathouse. Williams is shot and rolls into the water (dropping about 2 foot before splashing in). Pacino walks out of the house and meets the female officer. The camera pulls back to show the boat house on stilts about 20 feet out of the water.
Continuity mistake: When Al Pacino and Hilary Swank are talking outside of the building, the shots of Swank show the jeep in the background. Look at the front tyre: completely flat. A few scenes later it is being driven with a perfectly inflated front right hand tyre.
Plot hole: Days after Hap's killing Ellie finds a shell casing from a Walther handgun. I find it hard to believe that the police wouldn't comb the scene of a cop's murder enough to find a bright shell lying on black rocks.
Revealing mistake: When Dormer fails to pursue Finch during the log chase scene, he climbs out of the water by a ladder. If you look at Dormer's back as he gets out of the water onto the dock you can see an outline of the life jacket Pacino wore to film the scene. You can see the outline again when he turns around and walks up the walkway. (01:00:49 - 01:01:11)