Where else have we seen that sequence of events? In Star Trek: The Motion Picture. People always compare TMP to "The Changeling," but I've always found it bears a striking resemblance to this episode instead.
Arguably it's both. But I'm glad to see someone else get's the TMP / OfOPIM connection. I get the same vibe that I get when watching Changeling: "Good grief they just walked right off with this for TMP, didn't they?"
I'll go with Planets. I might need to watch Survivor again, but I have a really hard time getting around Shatner as Carter Winston. Doohan and Majel doing more than half the voices gets tiring, but the moment Shatner (or Nichelle Nichols for that matter) tries to do a new voice I think about organizing a re-dubbing project. (Was this Shatner's only "guest role" other than "young Kirk" from Counterclock?)
Also on the same topic Doohan as Bob Wesley in Planets is just awesome. It's the only time in TAS that not getting the original actor doesn't feel all that bad.