Well that happened to me, in my ranch a few days ago. I have reported it, however, i did not know this was the cause at that time.
When slimes, or maybe even other objects, are standing on top of an object, like a plort, and you pause the game for a long time, for some reason one of them keeps gaining speed while the game is paused.
When i unpaused my game, plorts and slimes have gone through corral walls, and some even went into other corrals, almost instantly creating Tarr.
I have recreated this glitch, and put it as a GIF.
