Really, I hadn't heard that before, doesn't surprise me though, that show was on the brink since its inception, haphazard was probably the only way it got done.
Yeah, Nimoy's role is small, I think its The Purple Testament or A Quality of Mercy, both of those are Pacific war oriented episodes, so I get them mixed up. Doohan is in season 4, Valley of the Shadow. I kept thinking I knew the guy, but he appeared thinner than I remembered. I looked up info about The Encounter, interesting stuff really, it said it was aired originally but never syndicated in the US. Also, the reason that it was pulled was because Asian-Americans, specifically Japanese-Americans complained about Takei's character being the son of a Japanese-American spy, which there apparently hasn't ever been proof of.
Thats another reason I like Serling and the show, he touched some pretty raw subjects, in season 4 there is an episode where Dennis Hopper plays a Nazi, can't help thinking it would have been a touchy subject, considering this wasn't even 20 years later.