When the Sheriff enters Dean's hotel room near the end, the lock is on the left side of the door. After their fight however, the lock is suddenly on the right.
When the boys are at the factory the first time. Dean finds a drawing of Frank's wife. When he tries to pick it up. He accidentally rips that drawing in half. Right across the middle. In the next scene Sam shows Luther's brother the drawing. Now only the bottom corner of the drawing is torn off.