James Doohan recorded the lines for Sarek but they were not used when it was found Mark Lenard was available to do the lines.
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.
This cartoon's view of Spock's hometown Shi'Kar has been added to the background in the remastered version of Amok Time (1967) in 2006.