I am trying to make a superman cake. The design has cracks all over and isn't smooth. I added crisco to try to smooth it but it still has all these little cracks. Totally new at cake deco so experts, what is the secret to perfect looking, smooth fondant toppers? (This is MMF, btw)

I think it was dry before you applied the fondant. Next time work the Crisco in while you are kneading the fondant. 

Is there ANY way to fix it???

I don't think so, just know for next time.