Plot hole: In the scene where the Wicked Witch is furious because Dorothy and pals have been saved from the poppy field, the Flying Monkey hands her a golden cap. She then dashes the cap across the room. The golden cap is used in the book to summon the Flying Monkeys. They shot scenes involving use of the cap, edited them out, but left this one with the cap inexplicably being tossed about. (00:57:05)
Suggested correction: I feel like this would fit better under trivia, or maybe stupidity. While it is true that the witch doesn't actually use the Golden Cap like she does in the book, I wouldn't really call something like that a "mistake."