Bugs bugs? Last minute of game juggle throws enemy flea way off map into the water, which results to the flea being magically moved into the game area alive and able to climb up the hill and play as normal.

Moving into the game area is what happens to things thrown off the edge of the map. If they are thrown into water then they won't take damage. Perhaps they should, although idk if this is cheap to detect.

Units that hit terrain off the edge of the map take progressively more damage depending on how far from the map edge they land, but they are still put back in the play area (often as wreckage).