In the opening credits, there is a six-second-long pause between William Shatner and DeForest Kelley's names, where Leonard Nimoy's name would normally be. It's only one second between each of the other names.
The film's villains were originally intended to be Romulans, but upper studio management wanted Klingons to be used, since they were better-known enemies. By the time the decision was made, the Romulan warship was already built, and they did not want the expense of replacing it. However, since Star Trek (1966) had already established that the Klingons and Romulans had shared technologies and ships in the past (for exactly the same real-world cost-cutting reasons), the idea of Klingons using a Romulan-style vessel was not a problem.
The U.S.S. Grissom was named after astronaut Virgil I. Gus Grissom, who was killed when the Apollo 1 spacecraft caught fire on January 27, 1967, during a launch simulation test. The fire also killed astronauts Edward H. White II and Roger B. Chaffee.
Production was endangered by the great fire at Paramount Studios. William Shatner helped fight the fire and rescue a crew member before firefighter reinforcements arrived. Shatner said that his motivation for doing so was purely to save a day on the shooting schedule, as he had to make a deadline to be available for shooting on a new season of T.J. Hooker (1982).
George Takei initially expressed reservations regarding the scene where the security guard called Sulu "Tiny". While Takei liked the scene overall, he felt that Sulu being called "Tiny" didn't make much sense, even when writer and producer Harve Bennett explained it was due more to the large size of the security guard. When Takei first saw this movie with an audience of fans, he came to recognize the scene (and Sulu's line "Don't call me 'Tiny'") as a real crowd pleaser, which changed his outlook to a positive reaction.
Grace Lee Whitney: As Janice Rand, Captain Kirk's yeoman in season one of Star Trek (1966), and who returned as transporter chief in Star Trek: The Motion Picture (1979). Appears during the Enterprise's docking sequence. She is the red haired officer in the spacedock lounge who shakes her head in disbelief, worried for her former crew, as she sees the ship's extensive damage.