The contagious entry thing used to have a bigger range.. On live I could jump across the narrow alley between warehouses, enter the door on the next-door warehouse, and be in the mission. Few teammates noticed, but if they did, I'd say "Shhh. VIP entrance."
Anybody else remember Doctor Door? For a long while the Devs couldn't find an elusive bug that would cause a small random amount of damage to characters going through doors. It was enough to kill you if you were down to your last few HP. So, they added a healing effect to the doors, enough to compensate, plus a little extra. The net result: you could heal up by bouncing in and out of the mission door a few times. Several issues later, they found the bug, and eliminated the heal. Made me sad.