I will say once again. Brer Rabbit was in the movie Song of the South. The stories of Uncle Remus and Brer Rabbit are years older then the movie. The movie, although you don't remember it, was about kid that had the misfortune of being in a very dysfunctional family, they incorporated Brer Rabbit as a way of story tell to get the boy to understand what things to value. So yes, in that respect it was part of the movie, BUT, everything in Splash Mountain could still be there without the movie ever happening with the exception of some of the music, which could have been written when the built the ride. They weren't and having songs like Zip A Dee, which was already a very popular, well known piece of music, made the ride fun and familiar. The stories were only a small part of the movie and not original stories at all. They were probably a hundred years old before they ever made it into the movie.