[HowardC]

Crap, that's right, thor WAS in it. Well maybe in this reality thor is the only norse god left. Or, judging by the first issue of zombies 3, maybe they got sucked into the nexus?

I think the main reason for the lip thing was so the reader could tell who the zombies are, joking and plot problems aside. I mean most of the marvel heroes wear masks, and many of them, like spiderman and iron man even wear masks that cover their face. It could be difficult for a slower reader to determine which ones are infected and which aren't without such an obvious deformity. Although personally, I think zombies that you can't identify right off the bat would have been far more frightening.