Continuity mistake: During the close up of Paul writing the word "Mark White" on the lid of the coffin, he is using his right hand. The shot then goes back to Paul, and he is writing with his left hand.
Continuity mistake: Near the start of the film when Paul has just taken the rope off his hands, he removes the gag from around his neck. It then cuts to a shot of him undoing his shirt. When the shot returns to the side view, the gag is back round his neck.