You didn't see many of their faces. I believe it was only one Immortal whose face you saw. They may have undergone a strict treatment possibly even worse than the Spartans. This particular person may have simply been a burn victim, or maybe some people have to make some sacrifice to rise in the ranks of the fictional Immortals in the movie. For instance, some of them may have cut out their eye --- this could be an entrance into manhood and so awe-inspiring they may become a general. You can tell they're used to that kind of shit because they don't look shaken at all by the wall of dead bodies.

And who makes a hole that big? It's obvious. That's how they traded with China.