Clearly Xehanort needed to start paying attention to what ELSE is on the train besides people. "... Can't say I've noticed, but I also didn't go looking."

He was going to have to now, someone's managing to fit a horse into a ball.

Magic is very obviously involved, but that wasn't enough detail for him! "Keeping pets in a pocket dimension seems kind of..." Mean. "...Unpleasant, but..." Well hey if it worked! And it wasn't killing anything? "When I can move without falling over, I'm going to find one of these people with large pets in tiny balls and ask to see it. It sounds ... really strange."

But it would also explain why there isn't poop everywhere. Poop stays in the pocket dimension!