Yesteryear

When this series premiered, George Takei was running for Los Angeles city council at the time. His opponents protested that airing any episode with Takei would violate the equal time law which states that political opponents must have equal time on television; so, although it is the second episode, in Los Angeles this episode was aired first, before Beyond the Farthest Star (1973), because Takei does not appear in it.

Commander Thelin's collar is black but is blue in some shots during the meeting in the briefing room.

Featured in Drawn to the Final Frontier (2006)