MGM owns the copyright to everything that’s unique to the Judy Garland film, from the character designs to the songs & music to the ruby slippers, so anyone making their adaptation of The Wizard of Oz can’t use that stuff without striking a deal with whoever owns the rights to MGM library now.

Return to Oz avoided most of that by just defaulting to W.W. Denslow’ s original book designs for the characters, though the Disney company was so hellbent on making that shitty Sam Raimi OZ movie from a few years ago seem like an official prequel to the Judy Garland movie that they paid for the rights to be able to use the ruby slippers and a few other elements from the Garland film, though supposedly they tried to go out of their way to make the Sam Raimi Wicked Witch of the West as close to the same shade of green as the Judy Garland version without duplicating exactly so they wouldn’t have to pay for that, too.