David Gerrold's original idea for this episode was that the tribble predators would breed as fast as the tribbles. Crew members would then begin to go missing, implying that the predators ate them. Producers felt that would be too violent for a Saturday morning cartoon.
This episode had been proposed for the original live action series. But producer Fred Freiberger disliked The Trouble with Tribbles (1967) and did not want another tribble episode.
This was the last of three episodes in which the cast recorded their dialogue together in the studio. The others were Beyond the Farthest Star (1973) and Yesteryear (1973).
A moment in the briefing scene when Kirk raises one of his hands over his mouth, lessening the amount of lip movements visible on screen, was added in because it allowed the animators to decrease the time it took to sync the character's lip movements to actor William Shatner's voice.
The robot grain ships that appear here introduce the first "new" Federation star ship design in the franchise since the Constitution-class. This design would serve as inspiration for the Antares-type that later appeared in the remastered Star Trek (1966).