Crew or equipment visible: As David and Amy Sumner drive up to their house for the first time, the camera crew is reflected in the car's side window.
Factual errors: When Amy fires the shotgun at the last attacker both the hammers are in the 'uncocked' position. She would need to pull the hammer of the relevant barrel backwards to cock the gun.
Continuity: After Amy tells David to get some lettuce, David notices the addition symbol on his chalk board changed to subtract by Amy earlier on, when he draws it back on, the symbol before it jumps from being an addition to a subtraction symbol.
Continuity: In the scene where David is going to confront the villages about the cat, he lets in 4 men but when they gather in the living room, there is only three villagers.