Due to the post-war German ban on Nazi-related imagery and paraphernalia, this was the only Star Trek episode that was not shown on German TV until mid-1990s, when these restrictions were gradually relaxed to allow for artistic expression.
Leonard Nimoy refused to have any publicity pictures taken of him in Nazi uniform. He was due to attend Hanukkah services later that month (filming took place in December), and did not want any controversies to arise.
This episode with its Nazi storyline proved rather difficult to make for a lot of the cast and crew who were Jewish. This included William Shatner and Leonard Nimoy.
All the Nazi uniforms used in this episode are taken from Paramount's costume storage, and were previously featured in many of the studio's World War II-era films. Many of them featured mismatched epaulets, collar tabs, and other rank-identifying insignia. However, McCoy's collar tabs, bearing a single silver oak leaf, correctly identify him as a colonel, as Kirk had ordered.
In one of the sequences of news footage, all of which consisted of stock shots and stock footage, a car with Adolf Hitler accompanied by soldiers is used to represent John Gill as the Führer on the planet Ekos. The sequence is a use of stock footage from Triumph of the Will (1935), the infamous Nazi propaganda film for whose production Leni Riefenstahl was responsible.