Who’s got the…

I think it’s well established by now that pony skeletons are, if not made of jello, rather divorced from that of a real horse. Given that various other quadrupeds like dogs, deer, etc can move around with surprising speed even missing an entire limb I can buy a pony being able to move at a slow pace on three legs without issue.
 
(There are a number of videos of 3 legged wild dear in particular that might give an idea what it would look like. Horses would be closer obviously, but those that lose a limb and aren’t just put down usually have some kind of prosthetic fitted. Although those in themselves could be mildly interesting if you’re wondering what a pony prosthetic might look like.)

How was Apple bloom standing using one hoof to carry the map?

What a Ludicrously Simple Map.