[Cosmic Tortoise]

Well, there's really only one spot where you can get out of the map, so I assume someone could easily modify the map to add an invisible barrier where you can jump down. Also, whoever does it could also fix the ammo issue at the same time. If no one wants to do it, I can give it a go.

It is also that you can get onto rooftops, which give you xray effect without showing yourself on Xmas Town.  You can hide inside the chimney on one roof, as it has no contact points, it is an illusion basically.  Several areas allow you to run outside the map rather than under it as well.  As stated earlier, it isn't a TTT map, only RP, hence the lack of ammo and map travel restrictions.

As per the Innocent Motel, that is a good TTT map, with traps, hidden rooms, and even a Detective Room.  It is very popular as well to the server.