Shari Lewis decided to write the romantic angle centering on Scotty as a way to deviate from the formula of Kirk always getting the romantic interests. This is the third show where Scotty actively pursues a specific woman. In season two, he wooed Kara in "Wolf in the Fold", and Carolyn Palamas in "Who Mourns for Adonais?".
This show was co-written by Shari Lewis and her husband Jeremy Tarcher. Lewis also lobbied to be cast in the guest role of Lt Romaine, but was denied the part. Lewis was a ventriloquist best known for characters such as Lamb Chop, Charlie Horse and Hush Puppy.
The glass-covered portal of the medical decompression chamber is a reuse of a suspended-animation pod from Space Seed (1967).
The overhead zoom shot of the bridge in the teaser was not shot for this episode. It apparently was filmed for (but not used in) The Galileo Seven (1967). Lt. Hadley, rather than Mr. Chekov, is at the Navigator station in the shot. It is noticeable that he is wearing Lieutenant stripes in the shot. The crew is also noticeably wearing the velour uniforms seen in season 1 and 2, not the nylon variety that replaced them in season 3.
This is the final episode in which we will see a Tellarite and an Andorian in TOS.