Continuity mistake: In the scene where Dewey and Ms. Mullins are in the bar, the shots from behind Ms. Mullins sitting down show that her left hand is on the table. However, the shots showing the front of Ms. Mullins show her arms folded.
School of Rock (2003)
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Directed by: Richard Linklater
Starring: Jack Black, Joan Cusack, Mike White, Adam Pascal
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More mistakes in School of Rock
Ms. Mullins: I've just been informed that all of your children are missing.
Trivia: Miranda Cosgrove, who plays Summer Hathaway, actually has a good voice and plays guitar. She had to take a 45-minute class to learn how to sing badly for the scene where she sang "Memories."
More questions & answers from School of Rock
Answer: It is never said but If I was to guess, they got it from the guy he was pretending to be (Ned's) information from the school office.