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Other mistake: Henry and Peter got on the school bus in the morning and Susan picked them up after school. Parents often drive their kids to/from school, even when busses are available. Busses usually aren't available for students within short walking distances to school. The day Peter looked "lost" when school let out, Christina walked him home. This indicates the school is close - close enough that Susan wouldn't need to speed to home and back during the talent show or take 45 minutes to execute the plan. (00:02:48 - 00:51:39)

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Trivia: During the opening credits, there are excerpts from Henry's red notebook outlining his plan. (00:01:20)

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Trivia: Although relatively rare and quickly dwindling, there are still some (100,000?) functional payphones (coin-operated or credit card) in the US, including in New York. It is doubtful there would be one outside of Henry's elementary school, but pay phones are typically near public buildings.

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Continuity mistake: Peter is sitting on his bed when he notices Henry's red notebook (or diary) sticking almost the whole way out of a cardboard box on top of the dresser. When Peter goes to pick up the book, there is a side view of the box - the book isn't there, and he has to put his whole hand inside of the box in order to reach it. If Peter was able to see the book while sitting on his bed, the book should have been visible when he was standing next to the box, but it wasn't. (00:59:42)

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Continuity mistake: In the treehouse, the contraption Henry built releases icing in a pile onto the top of the cupcake (or brownie) Peter is holding. When Peter moves the cupcake to his mouth, the icing is evenly spread in the middle. (00:07:04)

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