My friend who I introduced to the show, has since introduced some of her friends to Westworld. One of her friends had asked the question, "what is stopping one of the guests from killing the other guests?"

I honestly can't remember if this has been explained. I am on my first season re-watch on episode 5 and I do not remember if this gets explained/ talked about.

My friend, u/mangarooboo guesses that it is something to do with the guns.

She said, "Here's my theory. I think the guests aren't able to be hurt by anyone. Not just by the hosts. Guests can't hurt guests either. Because of the scene where they're eating and he says "you wondering how to tell which is which? Only way to find out" and pulls out the gun. Meaning if he shoots and they bleed, it's a host, not a guest."

I guessed that it's possible that the hosts injure more easily, therefore whatever bullets can bruise a guest, will ultimately kill a host.