During pre-production meetings, screenwriter David Loughery jokingly proposed to have Commander Uhura appear as an erotic dancer in order to lure away the hostage takers from the Paradise compound. He was surprised when the producers approved of the idea right away.
DeForest Kelley went into seclusion after filming the death of Dr. McCoy's father, because he was deeply personally involved with his own father.
Leonard Nimoy noted that this was the most physical film in the series, which reflected William Shatner's energetic sensibility and what he enjoyed doing most on the series - "running and jumping".
Sybok was originally named Zar, and in early drafts was unrelated to Spock. Harve Bennett came up with the Spock-Sybok family relationship to strengthen Spock's rationale regarding his actions relating to Sybok. William Shatner was opposed to the idea, feeling this was too gimmicky, and too much like a plot-line out of a soap opera.
Melanie Shatner: the yeoman that holds Captain Kirk's malfunctioning Captain's log. She also hands him his jacket when he first boards the bridge of the Enterprise.