during my experience, i encountered a zombie that would walk through the wall of any house that i was in. the zombie also managed to glitch me through the wall when i was attempting to punch it.also i'm not sure if its intentional or not but i didn't seem to be able to hurt it at all with the fists of the character, not to mention it seems that any contact at all with it will harm the character even though it doesn't seem to be using the attack animation much less facing the appropriate direction.