Other mistake: Maureen cuts her wrists with a razor blade. Days later, no bandages or scars.
Continuity mistake: In the scene when Carol is running from Marty, she hides in the gym. Marty runs into the gym. Carol runs out and goes down two flights of stairs. She then goes into a room by the stairs and goes to the window...the window that overlooks the gym. Somehow having gone down two flights of stairs Carol has ended up above the gym.
Continuity mistake: The amount of roaches in the bowl at the bar changes from less to more.
Continuity mistake: Torok the Troll wears a magic silver ring which allows him to appear in the form of Wendy Potter. However after Wendy's mother tells her about the orange juice, when Wendy touches the cold bottle of milk in the fridge she grabs her arm in pain and we can see both of her hands, and she's not wearing that magic ring.
Revealing mistake: When the bully's held up by Sam wires can be faintly seen.