Continuity mistake: At the beginning of the movie, when the girl is having sex with a guy, her legs are parallel to his, then it cuts to her sitting up on him. It's not physically possible for legs be flat on the ground whilst sitting up like that.
Continuity mistake: When the door slams on The Tall Man's fingers, you can clearly tell that no fingers are really sticking out of the door when the door actually shuts. (00:36:10)
Continuity mistake: When the sphere hits the man in the head it drains his blood. But when we see him lying on the ground there is no sign of the blood. (00:35:00)