The episode was written by Stanley Adams, who had earlier guest-starred as Cyrano Jones in The Trouble with Tribbles (1967). Adams has become concerned over the issue of overpopulation, and during production of Tribbles, mentioned to Gene Roddenberry that he thought it would be an interesting social topic for the series to address. However, Adams said that he was disappointed by the episode's final results.
McCoy makes a sarcastic remark regarding Spock having a career as a diplomat. Spock would later go on to have a career in diplomacy, negotiating with the Klingons in Star Trek VI: The Undiscovered Country (1991) and working as an ambassador during the time of Star Trek: The Next Generation (1987).
Remarkably, this episode did not run afoul of NBC censors, despite Kirk broaching such sensitive matters as sexual sterilization and birth control.
The coordinates given to Kirk to transport down to the council chamber were 875 020 079. The coordinates the council member gave Scotty, to beam him up from, were 875 020 709. This is not a "goof" but a (admittedly silly) plot device of the episode.
This is the only episode showing an exterior viewing port. The only other time a window looking outside the ship is seen is on the observation deck in The Conscience of the King (1966). Of course, in this case, the port seen is not on the real Enterprise. The exterior viewing port from this episode is the same design as the one used to witness Marta's execution in Whom Gods Destroy (1969).