Deliberate mistake: When Sarah, et al are surrounded by the Goblins in Goblin City, the first cannon fires causing an explosion in front of some buildings, one of which has a hanging sign with scissors on it. Later, after the squatty Goblin says, "Hey! I just fired you!" another cannon fires causing an explosion, and the very same shot is shown, only the first one was flipped. (01:20:15 - 01:25:35)