Daffy Duck and the Dinosaur (1939)

Continuity mistake: When Casper the Caveman takes off his caveman's outfit to go swimming, he puts his outfit near the edge of the bank. After Daffy says that he can't swim, he reverses back onto the land and goes and collects his suit, but this time the suit is now much further away from the bank.

Trivia: This was the final cartoon to have "VITAPHONE" and "Presents" on the opening titles.