After recently watching the re-mastered version of The Doomsday Machine, it reminded me of something that I always wondered about...why weren't any photon torpedoes used? Since it was obvious they could not penetrate the outer hull with phasers, didn't anyone think of shooting a few torpedoes "right down its throat?"
I'm sure the writers would simply have the DM gobble them up like M&M's but it was interesting that they weren't even mentioned. For that matter, why not aim the phasers "down its throat?"
Was it because the torpedoes weren't introduced until a later episode?