Not sure how to bug report this, but at the beginning of the game when you have to give a name and pick your character, you can select any of the characters that have the words "visit armory to unlock" for free. Just a silly glitch that doesn't really do anything.
a weird bug that I can't really screenshot: If you join a game as a spectator (at least in Zombie Rush mode) then sometimes broken windows in the game will appear as normal, and players that you are spectating will phase through them. This occurs with barricades as well.
Anyone know what the alien hunters are shooting at on the first level that you see them? I think they might be shooting at your warriors/hero, since one of my warriors kept dying randomly.
for anyone who has trouble catching the ghosts for potions - ghosts always float away from you and when they come in contact with a wall they will disappear. with some clever maneuvering you can buy just enough extra time to catch them and grab that extra health potion. hope this helps.