Continuity mistake: When Molly ties Tanya's whip around a bar to let herself down from the air duct, you can see as she slides down that the whip is knotted at intervals. But a few moments later, when the severed hand draws the whip back up, you can see that there are no knots in it.
Continuity mistake: When Tanya gets pulled into the fan Molly gets sprayed with her blood, and a couple of big red blobs land on her face. But when she runs into the art room seconds later, there is no blood at all on her face, not even smears where she might have tried to wipe it off.
Continuity mistake: When Pnub's head is picked off the kitchen table at the end of the hand-cutting scene, the ring of blood that formed around Pnub's neck stump is joined with the larger pool of blood that it came from. When Pnub and Mick come back to the kitchen later on, the ring is no longer attached to the larger pool. Blood does not evaporate like that when it dries.
Visible crew/equipment: Right after Anton's hand kills Mick, Pnub runs for the front door and manages to opens it a bit, but the hand slams it closed. During the brief moment that the door is open, you can see a light stand right outside on the porch.
Continuity mistake: Mick gets a dagger stuck in his chest near the end of the movie, and then Anton pulls it out. After the dagger has been pulled out, you can see there is no hole in Mick's shirt where the dagger was stabbed through it.
Factual error: When the bloke's head gets cut off in the beginning by the circular saw blade being thrown, surely there would be more blood, like when his mom got killed under the bed?
Continuity mistake: The cheesy puffs that are thrown to the decapitated head in the chair change from scene to scene.
Visible crew/equipment: When the mom goes downstairs to see what the sound is, she slips on blood and falls on the floor. When she starts to stand back up, you can see her knee pads.
Continuity mistake: When Anton is going to the dance and is backing out of the driveway in the pickup truck, you can see both of his hands on the wheel. This is after he has cut his hand off.
Revealing mistake: Pnub's (Elden Henson) head in the scene where Anton kills the two cops is obviously animatronic, it's eyes are clear blue and Pnub's eyes are brown.