Other mistake: Everytime it shows a window it is morning, even if the scene is supposed to be at night.
Other mistake: Right after the two girls have been taken in by Lucas and Annabelle, there is a scene where the girls are asleep. Lucas turns off a lamp and Annabelle turns off the overhead light switch; the room goes to complete darkness. However, when the camera pans back to the bed, there are two lamps/nightlights on in the room which would've provided light in the room even after Lucas and Annabelle turned off their lights.
Revealing mistake: In the first part of the movie when the dad finds the house in the woods after the car accident, he walks through the door with his daughters in the snow, and just before entering we can see he walks on a fake snow carpet.