Continuity mistake: When Wick and Stucky are arguing near the bathroom, the gun that Wick is holding changes from a silver revolver to a black one and then back and forth several times. Right before Ravelli busts in, you can see a clear shot of the gun, and it is black instead of the silver it began as.
Continuity mistake: The car belonging to the kids gets its windshield completely bashed in with seven blows (to the point where it partly collapses into the car) by Otis. When the car is later found and examined by the police, the windshield, save from a slight bit of damage in the center, is almost completely intact.
Continuity mistake: When the father and deputy look around the house and find the room where one of the girls is chained up, they start to use a wooden stake to open the chain. The scene changes to the sheriff in the house and the Slim Whitman songs begins and we see the wooden stake has been replaced by a metal rod resembling a fireplace poker.