Episode Behind the Scenes


John Harmon, who plays Tepo, had previously played the alley rat that Dr. McCoy accosted in "The City on the Edge of Forever".

This is the first and only time where a ship's phasers are set on a stun setting and used to stun a group of people.
Spock says there's no record of such a culture based on a moral inversion. Actually, the culture in the episode "Mirror Mirror" operates on somewhat similar principles, and Kirk & Co. presumably made a record of it and got some info on its background and history before they returned to "their" universe.
Originally Oxmyx and his men had trouble with the concept of transporters, but when Spock and McCoy beam down a second time, one of Oxmyx's men says they can't do anything until they're done sparkling. How'd they know this, when they didn't even know what a transporter was the last time?
In one shot Oxmyx uses a solid blue ball as a cue ball when playing pool.
When they first arrive, Kirk walks over and touches a bench. Then they cut to a close-up and Kirk walks over and touches the bench again.
At the joint meeting, when Kirk points a gun at one of the bosses who asks a question, the camera cuts to a close-up and he's holding the gun pointed upward at a 45 degree angle. Then they instantly cut to another shot and the gun is pointing at the boss again.