Since even before its official release, Overwatch has benefited from having an extremely active fanbase which recently found a glitch that allows two Mercy players to travel around the multiple districts of the Nepal map.
The glitch was discovered by YouTuber hulkman503, who revealed that the Nepal map is actually one massive map with three separate districts. This is the reason why the map has no real loading screens between rounds, but hulkman503 discovered that with two Mercys, some careful moving and a mountain without collision, you can actually move between the levels.
The glitch requires two Mercys because it needs both of their resurrection abilities to start it. The glitch will also require some time to master, as there are some death planes scattered around to catch you out.
Fortunately (or unfortunately), the control points on levels that aren’t being played aren’t active so you won’t be able to use this glitch to sneak in a win, but hulkman did reveal that the other assists such as health pickups are fully loaded. Players can also switch heroes on these levels at the base like normal, but the only way to return to the original Overwatch level is by dying.