The episode was written by Stanley Adams, who had earlier guest starred as Cyrano Jones in Star Trek: The Trouble with Tribbles (1967). Adams has become concerned over the issue of overpopulation, and during production of Star Trek: The Trouble with Tribbles (1967), 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.
When Kirk tries to address anyone on the ship, one of the shots, showing an empty corridor, is recycled from "Is There in Truth No Beauty?". Also, another shot shows an empty Sickbay - with the Red Alert indicator light flashing, an obvious pickup shot from an earlier 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". 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".