For two weeks after the airing of this episode, Mark Lenard received more fan mail than Leonard Nimoy.
In the first episode to feature Spock's parents, actors Mark Lenard and Jane Wyatt asked Leonard Nimoy for advice on how the two of them could display their affection for one another in a subtle way, since the Vulcans suppress their emotions, and it was Nimoy who had devised the Vulcan neck pinch and the Vulcan salute. Nimoy suggested they touch and stroke each others hand by the index and middle finger.
Actor John Wheeler, in character as Gav, had so much trouble seeing through the prosthetics over his eyes that he was forced to raise his head to see his castmates. This added to the early mythos that all Tellarites were arrogant as well as belligerent and aggressive.
Jane Wyatt was not familiar with the series and had assumed that it was a comedy after reading the script. But, on her first day of work, she saw that the cast and crew took the show very seriously.
Gene Roddenberry wrote the scene in which Amanda tells Kirk of the rift between Spock and Sarek. Writer D.C. Fontana felt that it would be inappropriate for her to discuss this with someone she had just met, but Roddenberry wanted Kirk to be more involved with the story.