Ha ha, you must have been so confused. The reason why Celes was a moogle instead of her character is because FF6 actually shares character slots temporarily. When you start a new game, there's a scene where a lot of moogles show up to help locke protect terra. These moogles actually share the same data slots as characters you meet in the game. FF6 swaps them with the other character once you meet them and name them.
I was playing a Hot Wheels game on the GBA, where all cars are unique and can't be picked twice by the cpu. But yea, so I choose a car and somehow a cpu picked the same, which isn't supposed to happen. I spawned inside him, and we started floating around the map, passing through walls. Or I was playing Need for Speed MW 2005, and during a police chase, an helicopter started acting like a police car and ramming me. Those things have an infinite mass tho, so it was quite a mess. I also saw them spawn in roadblocks a few times.