Little Man Tate (1991)

Factual error: In one scene Fred Tate is explaining to his mom, Dede, what a 'lepton' is. He says first "A lepton is a Z-particle", then furthermore says "Do you know what protons and electrons are? [...] Well leptons are even smaller." In fact, electrons *are* a kind of lepton. Also, there is only one Z-particle, and it is quite different from leptons.

Damon: You see, Fred, it isn't the size of a guy's IQ that matters. It's how he uses it.