Just watched this classic 2nd season episode again. It's corny, it's another silly parallel world, the science seems suspect to me… but gosh, it's fun!
Morgan Woodward is just terrific to watch as Captain Tracey, the marooned Star Fleet captain. We already knew he could do crazy/deranged characters well (he also played Dr. van Gelder in the Dagger in the Mind episode), but he adds to that here with carrying off the gravitas and authority of a Star Fleet captain, and he looks good in the fight scenes (very tall, he towers over Kirk!). He's in his early 90s now. WWII and Korean War veteran.
Roy Jensen has the role of Cloud William, the 'savage' Yang leader. He played professional football, which explains why he looks abut twice as wide as Kirk (again, Kirk looks completely outclassed in the fight scenes!). Does a good job in the role. Passed away 10 years ago at age 80. WWII veteran.
Irene Kelly has a minor role as Cloud William's girl Sirah. She looks great in her post-apocalypse skimpy outfit, gets to scream a few times (she's good at it!), then even has a key role in the ending. I'm not sure what was going on with her makeup, her face/skin looks odd in the close-ups. This was her first credited role: link
This episode mentions several off-screen battles between the Kohms and the Yangs, with Captain Tracey helping the Kohms with phaser fire. Would you wargame it? On one hand, it's the imaginary death of hundreds of Yangs. (But no blood!) On the other hand, how is it different from Rorke's Drift, except the natives (eventually) win?
This is a Roddenberry script, which might explain why there are so many plot holes. The Enterprise can't detect a plague before beaming down, a disease similar to one from Earth's past? Captain Tracey just happened to choose as his landing site the sole remaining Kohm settlement in Yang territory? The Yangs have become apparently illiterate, yet they speak recognizable English? McCoy eventually declares they can beam up at any time – won't they expose the crew to the same disease? Presumably, the Kohm settlement is massacred, which kind of ruins the 'happy ending'. Oh well, fun episode.
It kinda gets you in the heart when you see Old Glory… (maybe not the same for non-Americans!).