Character mistake: When Hollywood Montrose tells Jonathan Switcher that all the female mannequins have been stolen, they both run into the front window where there's a female mannequin.
Character mistake: The Daily Planet newspaper headline "New publisher for your favourite paper" has "favourite" is spelled the British English way. Since Metropolis is in the United States it should be spelled "favorite."
Character mistake: The little girl asks Kristen "what's your name?" Kristen replies "Kirsten". (00:05:59)
Suggested correction: I hear her say "Kristen." The transcript and subtitle even say "Kristen."
Character mistake: It doesn't occur to our heroes (admittedly kids) that you don't need to understand German at all in order to read it out loud. It's arguably easier to read than English! The only inscrutable letter would be "ẞ" but Scary German Guy's right there for help. (True, this is essentially what they end up doing in the end, but they still come about it through a "you don't need to be of age to be a virgin" realization rather than the even simpler "you don't need to know German.").