Continuity mistake: In the opening credits when the title comes up, there is a picture of Mater beside it with the Ghostlight after him. Mater has his right headlight still intact. But during the film, he loses his remaining right headlight moments before he is scared by the lightning bug, before the Ghostlight ever gets to him.
Continuity mistake: When Mater is hiding behind the Roman Coliseum of Tires, Luigi drives up to it as the fork lift finishes the last tire. In the wide shot, Luigi is looking slightly up and has his front end raised just a little. Then it cuts to a close up and Luigi is suddenly looking right at the forklift and has his front end lowered on the suspension.