Pit Stop has "inaccessible spawn hives". This means that the player cannot spawn in the room above the flag/bomb spawn. There are also invisible barriers blocking it off from people going up there via Brute Shot jumping, grenade jumping, and double jumping. It was added into matchmaking with Title Update 2 on 9/23/08, and was added along with Boundless, Epilogue, and Sand Tarp.
In the map description, "warlocks" are mentioned. This is likely a reference to the multiplayer levels Warlock and Wizard, from Halo 2 and Halo: Combat Evolved respectively. All three are similar in layout and gameplay, though certainly not aesthetics.
The inability to enter the rooms above the flag/bomb spawns was likely added to halt snipers from camping in the room, which normally makes an ideal sniping spot. The mention of camping in the maps description supports this.
It is possible to put weapons and teleporters in the room, but if you teleport, the room will be like a maze, with invisible walls everywhere.