Harry Potter and the Prisoner of Azkaban - Lumos Maxima
Witches and Wizards under 17 aren't allowed to do magic outside of school. It says so in the books and in the movies. Harry particularly reminded the minister of magic of that in the leaky couldron. Well, if so, why was he practicing Lumos Maxima in his bedroom? Why didn't he get expelled for doing so?
Anyway, obviously they did that so they'd have a cool intro. But, still....
A movie ticket, you eyes