Okay, dungeon, check.
Kirk points out, unusually astutely, that the things they have found are "Earth manifestations."
Too bad he wasn't serried about that in "Miri" when they found another Earth, but whatever floats your boat, I guess.
McCoy does think to ask if this could be a parallel development, but Kirk poo-poos that idea - too nightmarish. But it'll work for "Bread and Circuses."
Where it gets interesting is that the association Kirk is making here is that these things terrify people instinctively... all people. That's a little much. Even in the 23rd century, there are things that wouldn't apply across the board. Spock is half-human, but I wouldn't lay odds that fog would faze him - there shouldn't be fog on Vulcan. McCoy should be worrying about hurricanes and falling into swamps, being from Georgia and all (unless they've already got weather modification), and none of them come from a place with a disproportionate number of creepy castles...
And that's when ZombieSulu and ZombieScotty show up.