After the family escapes the basement, they're shocked when Gretchen opens the kitchen door. Gretchen was in the house and basement prior to opening the door.
The balloons that George grabs to throw at the witches aren't filled with water since they're floating on top of the metal tub and when he grabs them they squeak.
During the fight scene, Quinto refers to his cat as Ripley. During the end credit scene, he calls his cat Salem.