very good question. come to think of it there are lots of odd things like this in the actual show. like ponies lifting a ball with one hoof. or sipping from tea glasses. If you gave me the time I could think of some more but my point being that it's not that odd but I agree it is probably impossible.
lel.. maybe true.. but then again.. they are accustomed to their hooves like we are to our hands.. so they may have found a way.. though not like this.. not saying the picture is bad or anything