Arch-Vile gluing monsters together

When an Arch-Vile resurrects a dead monster, the game engine apparently does not include a check for other monsters walking across the corpse. Consequently, if the resurrected monster's sprite overlaps with another monster's sprite at the end of the resurrection sequence, the two become fused, and can neither move nor use ranged attacks until one of them is killed.

Because an Arch-Vile does not need to be touching a corpse in order to resurrect it, he can sometimes resurrect monsters on the other side of a wall. This occasionally results in a resurrected monster becoming stuck in the wall, and therefore unable to move or attack in any fashion (certain chaingunners on MAP31 of TEETH.WAD, for instance, are susceptible to this phenomenon).