Other mistake: When Nick fixes the doorbell, Kevin tests it and when he goes back to press it again, Nick pulls him back and doesn't make contact with the button but the doorbell sounds.
Factual error: The crescent moon above the window of the house in one brief showing is fake. The shadows throughout the film indicate if looking towards the front of the house, you're facing north. The moon in North America is not in the north part of the sky.