10 Movie Mistakes That Became Canon

10. Mrs. Teevee Doesn't Know Her Music - Willy Wonka & The Chocolate Factory

An oft-cited "mistake" in Willy Wonka and the Chocolate Factory occurs when Willy Wonka (Gene Wilder) plays a tune on the keyboard to open the door to his chocolate room - a musical piece which Mrs. Teevee (Dodo Denney) confidently identifies as "Rachmaninoff."

But as it turns out, Wonka wasn't playing a Rachmaninoff composition at all, but rather Mozart's overture to the Marriage of Figaro.

It's a gaffe that surely flew over the heads of most young viewers, though adults familiar with classical music have often pointed out the supposed error.

Yet on the film's DVD commentary, it was clarified that this wasn't really a mistake at all - it was simply intended to demonstrate Mrs. Teevee's know-it-all personality, that she's not nearly as smart and worldly as she evidently thinks she is.

Ironically, it also ends up making those who point it out as a mistake seem a little over-confident in their own powers of observation, given that they missed what it was actually supposed to indicate about the character.

Though it's been parroted as a mistake for literally decades, those in-the-know have made it abundantly clear that Mrs. Teevee is the ignorant one - not author-screenwriter Roald Dahl.