If Doorman places an active door in a corner, using a heavy melee attack or dash to move toward the corner allows him to clip out of bounds. This seems to work on most of the corner areas i checked on the map.
I have not tried this in an online game so i am unsure if there are any protections against it in live games.
I have not tried this in an online game so i am unsure if there are any protections against it in live games.