1st Mar 2011
Other mistake: Toto is listed in the end credits as being played by Toto, when she was actually played by a dog named Terry. A few years after the film was released, Terry's owner/trainer, Carl Spitz, changed the dog's name to Toto due to the popularity of the film, but the credit is wrong for the time.
Suggested correction: It was probably done on purpose to promote him as Toto, not as Terry, even though the dog was well known both before and after this movie for appearing in many movies. Her most famous movie before Oz was Bright Eyes with Shirley Temple.
1st Mar 2011
Revealing mistake: When Toto reveals the Wizard by pulling the curtain aside, he doesn't use his mouth; the curtain is tied to the dog. Dorothy can even be seen later removing the rope.