There was a bug that was funny for a moment. One of the object types is a movable or mob (moveable object). These are barrels, chests and other big objects you can push, but not pick up. Somehow all of them were moving randomly around. That was a bit hilarious and I was just chasing them for a while. Everything seemed to work well, you could push them like always, they didn't just want to stay in one place. The reason was that when the movable is on water it's floating and moving randomly, but in this case the moving routine was called every turn no matter where the objects were.
This bug could be made a spell, some kind of chaos spell that animates objects to move around and cause confusion among mundanes.