I know of 2 ways out of der riese and alot of barriers....
In the room with the type-100 there is a room with grenades on the wall next to a window just get it so the bottom board is only one left (similiar to verruct) and start+triangle when a zombie pulls the board and so get pulled out into a room and hallway but cant go far.
second way is the room with the double barrel on the wall before mule kick room, any round past round 4 get a running zombie and run it in a circle, then hugging left wall as you go oout from mule kick room to double barrel room after the window will be a post go prone and hold left on left analog stick and should get pushed outside the map.
lol just remembered the 3rd way but once your there cant help or do anything down there, but its similiar to the second way but go to the room with mp40 on the wall look for the tesla coils on the far right side of the teleporter and get a running zombie and prone close to the wall and coils the running zombie will push you completely out of the map but you cant shoot the zombies above you cause there is another barrier between you and the zombies.
You can also get out of shagrila aswell...
and if your host only way for you to get out of the map is a lag switch, unless you hit start and change your sensitivity up or down the bigger the change=more lag, then hit circle and just before board comes off hit triangle and it should lag you and everyone else for a bit most of the time around 5 to 10 seconds, then just exit back to game and run a bit away and change the sensitivity back and your golden.