Touching again on Judy Garland and the ill-fated blonde wig - original director Richard Thorpe had a dramatically different vision of the final film than what we saw on film. His desire to see Garland in a blonde wig with heavy makeup was actually borne of his frustration with her casting. He'd originally wanted Shirley Temple to play the role.
Thorpe saw the original books as more of a fantasy-horror tale and wanted this to be the look of the film, too. That was totally at odds with the more Disney-esque tale that studio MGM were looking for. As his suggestions were turned down and overruled on a day by day basis, Thorpe became an increasingly unhappy camper within the production, and it's likely he would eventually have resigned had he not been fired. Fortunately for Thorpe he didn't struggle to find work afterwards, and he now has a star on the Hollywood Walk of Fame.