I've noticed that when I am looking at the other side of a closed fence with a back entrance (that I've never seen) my character still knows EXACTLY how to get there. Enemies seem to be the same way, which would be excusable if it was just a single fence and they knew the area, but they actually instinctively know that a back entrance has opened that was closed before, despite not having seen it happen.
The fix would probably be: don't let path-finding function through unexplored areas and if a door was closed the last time someone saw it, that someone's path-finding shouldn't lead through it normally.
