We never even noticed.

It seems that Emma Watson was too pretty to play Hermione in Harry Potter. If you read the books you will recall that Hermione Granger was described as having bushy hair and large front teeth. In order to cast Emma Watson and stay true to J.K Rowling's vision, director Christopher Columbus said he wanted to give her fake teeth. And though she wore the fake teeth in the movie, it wasn't for very long. Speaking to Entertainment Weekly, the director said: “The thing we shot on the first day of Sorcerer’s Stone was the final train sequence where Harry looks at Hogwarts and Emma, Dan, and Rupert are huddled outside of the train,” “It was a big thing in the books about her teeth. She sort of had an overbite, so she's wearing fake teeth in that scene.” Did you notice this? While it seems like a good idea to make her look as much like book describes, Columbus said he quickly realised it wouldn't work. "I realised that she's never going to be able to perform with these huge fake teeth in her mouth for the rest of the movie," he added. So it's only for one scene at the very end, but we're very surprised more people didn't notice this continuity error.