When John Cusack is sitting in his car with his partner he sheds a tear which runs down his cheek. In the next shot he is shown and his cheek is dry.
Similarly when John Cusack's daughter is first brought into the basement and is hanging in chains, she, too, cries with a tear running down her cheek and in the next shot her cheek is completely dry.
When Carl comes into the cellar to get Abbey for dinner, she's managed to change into a dress even though her hands are chained together and could not possibly put her hands through the two sleeves without them being unlocked by Carl who has the only key to the locks.
When Carl removes the corkscrew from his chest, he twists it clockwise and then pulls it out. Twisting it that way would only screw it in farther.
When Kelsey reloads the shotgun she uses a shell with its primer clearly already used, and thus the gun cannot be fired.
When Abby gets a light for her cigarette, the killer holds the car lighter against the filter end of the cigarette.