That cake is AWESOME! What a lucky little kid!
As far as the fondant goes...one thing I've learned from making cakes with fondant is to make sure the icing used underneath is extremely smooth, wipe away any little "spikes/whips/blobs" prior to putting the fondant on.
I don't know if you chilled the cake after applying the icing or if you put a crumb coat on first or not but that does help and makes it easier to smooth the rough spots down.
But seriously, cutting cakes like that isn't as easy as it looks so mad props for you!!