Continuity mistake: In the first movie the "Welcome to Silent Hill" sign is on the right. In this movie it's on the left.
Continuity mistake: When Frost is checking the documents at the Counterfeiters house, Frost borrows his glasses and in a quick camera shot of the Counterfeiter he is wearing them even though he has passed them to Frost.
Continuity mistake: The chronology of the date stamp used during the police camera footage is accurate, starting from 04/11/11 and ending at 08/17/11. However, officer Taylor fills out his paperwork after a bust dated 8/19/12.
Continuity mistake: In the underground lab, Dr. Su offers to surgically remove the false memories he implanted in John's brain. He drills a half-inch hole in the right side of John's forehead, which leaves the right side of his face covered in flowing blood. John can't stand the pain, breaks free, and he goes on a rampage throughout the underground bunker, killing every UniSol in his path. As he fights his way through the bunker, the bleeding hole in John's head switches from the right side of his forehead to the left side, then back to the right side again. Also, in the last scene (an unspecified amount of time after the bunker brawl), John has no scar on his forehead at all.
Continuity mistake: After the funeral back at the house, Nicole's sister Annie goes to the bathroom and undoes her belt to sit down to pee, but when she hears a noise and stands up and pulls her pants up, her belt is buckled.
Continuity mistake: The man with one arm in the projector slides shows his right arm removed below the elbow. The next slide shows his left arm missing, and then it goes back to his right. (00:35:34)
Continuity mistake: When Sheriff Cooper writes "Karsson" and underlines it on the chalkboard, the way it is written changes between shots. In one particular shot, the line he underlined it with is suddenly rubbed out.