Factual error: Marie plays a horn solo on the beach. At times continuous sound is coming out of the horn while she is inhaling through her mouth. Horns only produce sound when the player exhales.
The Jerk (1979)
1 factual error
Directed by: Carl Reiner
Starring: Steve Martin, Bernadette Peters, Mabel King, Catlin Adams
Revealing mistake: When the sniper is shooting the cans, the close-up of the first can shows the metal peeling out as though the bullet had come from inside instead of outside.
Mother: Navin, it's your birthday, and it's time you knew. You're not our natural-born child.
Navin R. Johnson: I'm not? You mean I'm gonna stay this color?
Trivia: The Cat Juggler, in the film, was Steve Martin. (01:12:40 - 01:13:30)
Answer: Navin self-applies the "Jerk" epithet early in the film, using it not in the sense of someone obnoxious or mean (as it is used in most cases), but in the sense of a stupid person. He's saying he blames himself and his lack of intelligence (though, as you say, it is usually simple naïveté) for ending up where he is (broke, homeless).