Star Trek: Phase II was an unproduced television series created by Gene Roddenberry as a sequel to Star Trek: The Original Series. It would have featured most of the original crew, minus Spock who would have been replaced with a full vulcan named Xon. However, Barry Diller, Chief Executive Officer of Paramount Pictures, decided the pilot, "In Thy Image", would work better as a feature film, and the series was eventually converted into Star Trek: The Motion Picture.

The 21st Street Mission was a homeless shelter organized and run by Edith Keeler around the time of the Great Depression. Kirk and Spock find jobs there while they search for Dr. McCoy.

A month before the film's release, Anton Yelchin died in a freak car accident. During the ending credits, there is a dedication caption which reads: "For Anton".

When Kirk orders Dr. McCoy's commission reactivated in Star Trek: The Motion Picture, a resentful McCoy complains of being "drafted".

After rescuing Scotty, Jaylah takes him to her makeshift home, the grounded U.S.S. Franklin, an early Starfleet vessel reported missing over a century earlier.

In "The Apple", the crew of the Enterprise visits Gamma Trianguli VI, a tropical planet whose primitive inhabitants worship an ancient computer called Vaal.

Sofia Boutella plays Jaylah, a scavenger who teams up with the Enterprise crew to defeat Krall.

Leonard McCoy served as chief medical officer of the U.S.S. Enterprise under Captain James T. Kirk who often called him "Bones".

Miles O'Brien originally served as transporter chief of the U.S.S. Enterprise-D. He was later promoted to Chief of Operations of Deep Space Nine.

Janice Rand was the Captain's yeoman on board the U.S.S. Enterprise and first appeared in the episode "The Man Trap". She was originally intended to be Kirk's love interest, but was released midway through the first season.