Vertical Wall Warp
Vertical Wall Warp is a glitch, found by Mike, which allows quickly getting on top of OoB walls. To perform the glitch, crouch in a portal, jump, and save and load the game immediately. This should teleport you on top of the wall, allowing you to walk along the ceiling of the map. If the portal is at the top of the wall, you can also get save glitched by save loading again (see the current 10 oob route).