Revealing mistake: When the security guard finds the wizard as he appears on the bed, the guard's reflection can been seen in the doorway. (00:43:10)
Continuity mistake: Julia (Christina Applegate) puts a "Hello My Name Is..." sticker on Thibeau's tunic with her phone number on it. Only part of the sticker is visible. When he turns around to walk down the stairs, it is fully visible. A moment later when he stops the purse snatcher, it's gone. Three seconds later, talking to the woman dressed as a witch, it's back again. (00:50:15)
Revealing mistake: When they are driving back from the museum Thibault and Andre are both feeling sick and Julia asks Hunter to slow down. Hunter mentions that they are only doing 22mph and Julia replies "can you try going at 21?" However in the background a passer by is jogging past them - that's a pretty fast jogger.
Continuity mistake: When Thibault enters the bar, his "Hello, my name is." sticker is now crooked, as opposed to the last time we saw him and it was straight.
Continuity mistake: Right at the end, when Julia is at the castle that she got, when she is walking by the cannons you can see that she has black boots on. But in the next shot when the old man is talking, if you look hard enough in the last frame of that view, she is wearing white, high heel sandals.
Factual error: The movie takes place in Chicago, where the police wear distinctive checkerboard bands on their caps. However, none of the officers shown in the flick wear these bands.
Deliberate mistake: Just after arriving in the 21st century, Thibault and André enter an elevator and scare away its occupants. Attempting to chase them, the elevator doors close despite their attempts to keep it open. Elevators have a safety mechanism which opens the door when they encounter resistance. This was ignored deliberately in the film for comic effect.
