"Shore Leave" is kind of a "tongue in cheek" episode. I mean c'mon... the fake rabbit costume? Alice in Wonderland? The reaction to that as well? McCoy didn't go into any detail about exactly what he saw. "Large rabbit" yes... but did he say "Large rabbit costume
?" No, despite those being very important characteristics to note. He did say that the rabbit claimed he was late, but not that he accurately quoted from the Lewis Carroll novel. That would also be a very important point; a true mimicry of Alice in Wonderland, on an alien planet many light years from Earth?
Nevertheless, it's a kick of an episode, a lot of fun. There are some very serious moments too. It isn't all fun and games. And that's what makes it so great... the combination of humor and fear in one episode. This is in contrast to "I, Mudd", which is pretty much a farce all the way through.