8. The film had several directors over the course of its production
The first director of the film was Richard Thorpe, followed by George Cukor, who worked on the production throughout some of its planning, rehearsal, and scriptwriting phases. But he did not shoot any of the film, and when he left it in November 1938 (to begin work on Gone With the Wind) the production was badly behind schedule. He was replaced by Victor Fleming, whose name remains on the credits of the final film. But he did not finish the film, including the final editing process, and the filming and recording of Over the Rainbow.
Fleming was called to rescue the troubled production of Gone With the Wind in February, 1939 (he eventually collapsed from exhaustion while finishing that film) and MGM replaced him on the Oz set with King Vidor. Vidor filmed nearly all of the Kansas sequences of the film, including the tornado and the scenes Dorothy viewed from the window of her house as it was carried by the twister to the land of Oz. He was not credited for his work on the film. Victor Fleming won the 1939 Academy Award for Best Director, but it was for Gone With the Wind.