The biggest gitches I find with zombies is that buildings seem non existant to them they glitch through walls doors the floors and stairs don't exist with them as u can go up the stairs and they just glitch through into the next room downstairs they also have a very high range that they hear you from and hit you even after you have gotten out of the way and yes respawning very near where you just killed them I think that's about all the zombie gliutches I have come across so far