Continuity mistake: If you look carefully at the monster (Frankenstein) you will see that his face is different in the ending scenes. The reason is, during the movie you see the monster take the woman doctor and throw her out the laboratory window. You then see the monster kind of stumble, which he really did and broke his ankle. So in the final scenes they replaced Lon Chaney Jr. as wolfman with a stuntman, and Lon Chaney Jr. finished the movie as the monster.
Continuity mistake: In the scene where Judy Garland and Fred Astaire go to the nightclub to see Ann Miller, Ann invites Fred to come up and dance with her. When she is dancing by herself, she is wearing red high heels. When Fred comes up, she is wearing red flats.
Continuity mistake: In the opening scenes, the Red Witch has her lee rail almost awash, yet the view on deck and in the cabin following, the vessel is perfectly upright.
Continuity mistake: While fishing, Mr. Peabody hooks a mermaid who is swimming underwater. When he reels her in and she leans over the edge of the boat, her hair is completely dry and perfectly coiffed.