The Wonderful Wizard of Oz by L. Frank Baum

I hadn't read this in years - lots of years. Long enough that I "remembered" more of the movie than the actual book. In most respects the movie is very faithful to the book, with the exception of the whole "dream sequence" thing where the fantasy characters - the Scarecrow, the Tin Woodman, the Cowardly Lion, and the Wicked Witch are just acquaintances transformed by her dream. But there is one detail - why did the make the magic slippers that take Dorothy and Toto home in the end ruby instead of silver like they were in the book? It seems like an unnecessary change.