Was The Wizard of Oz the first color film?
While the dramatic transition from the sepia-toned Kansas opening to the vividly colored land of Oz amazed its original viewers, The Wizard of Oz wasn't even close to being the first color film.
As for which was the first color film... there's no one answer. It depends on how you define your terms—both "color and "film"—and even then we have no idea. Hand-colored film frames were used almost as far back as film frames themselves. Early "black-and-white" films were often black-and-sepia, or black-and-blue, or sepia-and-white, with the foreground, background, or both being tinted.
Later processes included alternating frames shot through different color filters, simultaneously showing two seperate film strips through different color filters, and various methods for putting multiple colors on one filmstrip. Even "Technicolor" was a name used for several different processes over the years.
Plausible claimants to the title under various definitions span the years from the 1890s to the 1910s, and those are only the films we know about. The most famous version of the Wizard of Oz, starring Judy Garland, was released in 1939.