While I can agree that many of the cartoons that Warner Brothers pulled from circulation were quite racist, I think they made a big mistake in the case of "Mississippi Hare". First, I doubt if many people would in any way consider it racist--and I don't think we should always cater to those who the easily offended. Second, it is a pretty good cartoon and it's a shame to ban it (officially or unofficially).
The film is set in what appears to be the antebellum South. It begins with a black worker picking cotton and accidentally dropping Bugs Bunny into a hopper that then transfers him to a river boat. What, exactly, is racist about this? In those days and after, a huge majority of people working in the cotton fields WERE black Americans. Should they have made them white or green so as not to offend?! Plus, the person is just a person--no stereotypical facial features (or ANY) are seen--just a brown-skinned arm. My attitude about this is just get over it--it IS a part of our history, like it or not! As for what happens next, Bugs has a run in with Colonel Shuffle--a gambler who is angry Bugs beat him so badly at poker (or course, Bugs having six Aces might also have something to do with it). During the rest of the film, Bugs does he did best with Elmer or Yosimite Sam--he terrorizes the victim repeatedly for our viewing pleasure. It's all pretty funny--particularly the final line. My advice is to download it from archive.org--you're bound to enjoy it.