Nicholas Meyer, director of The Wrath of Khan, did not return for this film because he had disagreed with changes made to his previous film's ending without his consent.

Studio chief Michael Eisner was initially reluctant to hire Leonard Nimoy to direct because he mistakenly believed the actor hated Star Trek and had contractually demanded Spock's death; Nimoy had to convince him otherwise.

Producer Harve Bennett wrote the screenplay starting from its ending, where Spock says 'Your name is... Jim,' and worked backwards from that point, completing the script in six weeks.

The villains were originally written as Romulans, but Nimoy preferred using the more theatrical Klingons instead, comparing their pursuit of Genesis to the Soviet race for nuclear weapons.

Bibi Besch's character Dr. Carol Marcus was originally intended to return but was cut for budgetary reasons and because her knowledge of her son's unethical use of unstable protomatter was hard to reconcile with the story.

Kirstie Alley did not reprise her role as Saavik from The Wrath of Khan; she was replaced by Robin Curtis, who was recommended for the part by a friend at Paramount's casting department and was cast by Nimoy the day after their meeting.

Dame Judith Anderson, who played the Vulcan priestess T'Lar, was 87 years old and only about 4 feet 8 inches tall despite claiming to be 5'2"; costume designers used an overlong hem, built-up shoes and a crown to add six inches to her apparent height.

Spock's rapid aging on the Genesis planet was portrayed at four different ages by four different child and teen actors (Carl Steven, Vadia Potenza, Stephen Manley, and Joe W. Davis), with Frank Welker providing his screams and Steve Blalock doubling for Nimoy, totaling seven actors for the role.

George Takei was upset that his character Sulu was called 'Tiny' by a guard in the film and argued to have the line cut, but changed his mind and apologized to the producer after seeing the finished film.

To guard against leaks like those during The Wrath of Khan's production, Paramount used heavy security measures: Spock was referred to in scripts as 'Nacluv' (Vulcan spelled backwards), Nimoy's name never appeared on call sheets, and scripts were chemically treated with subtle wording differences to trace leaks.

Aside from a single day of location shooting at Occidental College for the Vulcan stairs scene, the entire film was shot on Paramount and ILM soundstages.

Production was briefly shut down after a fire, later ruled to be arson, destroyed several soundstages at Paramount adjacent to the Genesis planet set; William Shatner was among the cast members who grabbed fire hoses to help fight the flames.

The Klingon captain's pet creature, nicknamed 'Fifi Rebozo' by the crew, was puppeteered by visual effects supervisor Ken Ralston hiding inside Kruge's command chair, operating its spring-loaded jaw with his hand.

The Klingon Bird of Prey's cloaking effect was achieved by simply throwing color separations out of sync to create a blurry ripple, a simpler and more effective solution than an earlier, more elaborate animated concept.

To destroy the Enterprise model on screen, the crew used cheaper substitute models rather than the original $150,000 miniature, employing techniques like acetone-dissolved Styrofoam, burning steel wool, and a talcum powder-covered plaster dish for the saucer explosion.

William Shatner dieted before filming to lose weight but tended to gain it back as production continued, requiring the costume department to make 12 different shirts to accommodate his changing size.