This is an extremely rare Mighty Mouse cartoon, banned because of its racial stereotypes so there's a good chance this will never seen the light of day again, unless you find it in bootleg circles (as I have).
In black and white, the cartoon starts off pretty strange as Eliza and her baby go to the "starting line" with the infamous Simon LeGree and his snowdogs. Uncle Tom, who starts the event, even asks everyone if they're ready ("Is the dogs ready?").
Once they're off, LeGree then chases Eliza through a winter wonderland of ice and snow. Of course during the chase Eliza comes across a giant slot machine that she has to play. Mighty Mouse ends up getting a call (from Little Eva) in his hideout and comes to "save the day" once again.
One thing of interest is something at the start of the cartoon during the titles which indicated the cartoon was for home use only or something along those lines. So perhaps this was something people could rent out or buy to bring home, much like VHS tapes and DVDs years later? Definitely a cartoon Mighty Mouse completists would want for their collections.