Actor-Inspired Element: The final interaction between Kirk and Spock was written, word for word, by William Shatner, even down to the blocking of the scene and having them be physically separated at the moment of Spock's death.
Matt Jefferies, designer of the original Enterprise bridge (and namesake for the "Jefferies tubes" used throughout the franchise), said that after The Motion Picture he "never watched" subsequent films or incarnations of Star Trek, remarking that they had turned his Navy-esque bridge into "the lobby of the Hilton."
Forget Khan; by now, the real villain of Gene Roddenberry's life had entered the stage: Nicholas Meyer. Gene Roddenberry hated the militaristic framing of WoK as it developed (though he later praised/claimed credit for the "Hornblower in space" theme, it was not his idea), accusing it of not staying true to his ideals of what Star Trek should be. Meyer was then a young man, a newcomer to Hollywood, full of vim and vigor, and in no mood to take crap from a fossil like Roddenberry. Their struggles, which threatened to overshadow the film itself, are chronicled in Meyer's memoir, A View from the Bridge. After it came out that Gene had been sick, and was being fed orders from his parasitic attorney, Meyer regretted losing his cool at him.
Many people, including Harve Bennett, believed that Roddenberry was responsible for Spock's death being leaked to the public, knowing the backlash it would receive. (Meyer got death threats, probably hoping to scare him away from the film.)
Leonard Nimoy and Nicholas Meyer very nearly got into a shouting match during the filming of Spock's death scene, according to Nimoy's autobiography I Am Spock. The cause was that they had differences on how gory the scene should be. Meyer wanted Spock visibly bleeding green from open sores and leaving a very visible green handprint from his Vulcan salute, while Nimoy thought that would be undignified, borderline narm and would distract from the gravitas of the scene. Add into the mix that Nimoy recalls being physically distressed at killing off Spock (as mentioned below under What Could Have Been, he had rekindled a desire to keep the character going), and the fuse was lit. In the end, Meyer backed off and toned down the blood.
Dyeing for Your Art: Ricardo Montalban engaged in an intense workout regimen to show that Khan is still a force to be reckoned with. Those pecs you see throughout the film? All real.
According to Meyer, lawyers decided who got credited, and paid, for the screenplay. "I just wrote it and they put somebody's name on it."As for the whole story The full story: before Nick Meyer was hired as director, there had been five different previous drafts of the script (four written by Jack B Sowards, one by Samuel Peeples)—all with considerably different plots and all unsatisfactory. The special effects company needed to have a proper screenplay for the film within twelve days or the movie basically wouldn't happen, so Meyer volunteered to write a definitive screenplay within twelve days which would combine all the best aspects of the previous drafts. Upon being told they wouldn't even be able to organize a screenwriter's credit for him in twelve days, Meyer decided to do it anyway and try to organize a deal later. In the end he actually did complete the screenplay within twelve days but ended up going uncredited and unpaid for it, with Sowards getting the sole credit.
Judson Scott (Joachim) doesn't appear at all in the credits, due to an overzealous agent trying to get him star billing without his knowledge.
If one knows the dialogue when Spock and Saavik speak Vulcan, one can see that they are speaking English and it has been overdubbed.
No Budget: Not completely, but given the cost overruns on Star Trek: The Motion Picture, they definitely had to save money wherever they could. There isn't much in the way of new sets; the remains of the Botany Bay, Regula I (even this was just a modified model from the first film) and some corridors. The movie is largely a Bottle Episode. The Klingon ships in the training simulator, all of the Enterprise shots in drydock and the "beauty shot" after its launch were all recycled from the first movie. Several uniforms were reused as well—the thruster suits, engineering suits, and McCoy's medical shirt were reused straight-up with only minor tweaks, and the one-piece jumpsuit uniforms were dyed and tweaked into the cadet/noncom jumpsuits. Even Spock's black robe is from the first movie.
The character of Joachim, recast and slightly renamed, from his appearance in the original "Space Seed".note According to one novelization, it's actually the original's son.
Lieutenant Saavik is played by Kirstie Alley in this movie and by Robin Curtis in the following two movies.
Promoted Fangirl: Kirstie Alley was a big-time fan of the original series who was extremely excited to be able to play a role alongside Leonard Nimoy. Apparently, she was quite apt at the Vulcan characterization, which helped to land her the role. Sadly, she did not come back for The Search for Spock, though exactly why is not clear. Some sources claimed that she chose not to return because she was afraid of being typecast as a "science fiction actress", while other sources claim that her agent demanded too much money without her knowledge or approval, hence her being replaced by Robin Curtis.
The Enterprise and Reliant bridge sets are in fact the same set. It was designed modularly so that the different sections could be switched around to present a different layout.
The Reliant studio model is built largely from spare Enterprise model parts with a few additions and one major notable subtraction (the secondary hull is removed entirely with the nacelles grafted directly onto the saucer section).
Pointedly shown with a background shot: when Chekov and Terrell are arguing about Carol Marcus's reaction about "transplanting" the life forms from Ceti Alpha VI, Checkov is standing beside a monitor showing the lower hull of the Enterprise.
Separated-at-Birth Casting: Actor Merrit Butrick, who played Carol Marcus's and Jim Kirk's love-child David, really does kind of resemble a young William Shatner at times.
Throw It In: Harve Bennett accidentally saw the Reliant's designs upside down, and the crew made the models to fit that.
Unintentional Period Piece: In the director's commentary, Nicholas Meyer paraphrases Orson Scott Card's claim that all works are a product of their time, when it's pointed out how Khan's followers look like the entourage of a hair metal group.
Spock'sHeroic Sacrifice was originally placed at the middle of the movie, in an attempt to mimic the Psycho gambit. When they wisely decided to make it the emotional climax of the film instead, Peter Preston's sacrifice was put in its place instead. Similarly, the whole ordeal was practically spoiled before the movie began filming because it was what lured him back to the franchise. The Kobayashi Maru sequence was intended as a way to throw off expectations.
To elaborate: An early version of the script got leaked, including the fact that Spock died. Afterwards, the Kobayashi Maru sequence, which included Spock fake-dying, was added to fake-out moviegoers and make them think that that was the "death" that had been promised.
Ricardo Montalban considered turning down reprising the role of Khan due to lack of screen time. When he realized how much of an impact Khan has (even when he's not on screen, Khan is affecting every action every character in the movie takes), he signed onto the film.
The preliminary design◊ for the U.S.S. Reliant was initially much different than what was eventually seen in the film, with the "roll-bar" torpedo bay missing and the warp nacelles above the dish, like on the Enterprise. However, when Harve Bennett received the design for approval, he viewed the drawing upside-down and assumed that was Reliant's intended look. The production team debated whether or not to send the drawing back to Bennett right-side-up, but he was shooting in Israel by then and there was little time to contact him. They added the roll bar and repositioned the nacelles, resulting in the Reliant we are familiar with.
Even before that stage, they originally considered having the Reliant be another Constitution-class starship (it was the only class of Federation ship seen on Trek before that time), but then realized the audience would have trouble telling it apart from the Enterprise during the battle sequences. Thus it was decided to make Reliant part of the Miranda-class.
Spock's death was originally intended to be permanent, as Nimoy had grown tired of the franchise and even almost didn't come back for the first film, so he signed on for Wrath with the understanding that Spock would die. However, working on this film was such a good experience he rethought his decision.
Nimoy: As it came time to film the scene [Spock's death], I thought "I may have made a big mistake here." I had no idea this thing would ever go again, but here it was, cooking on all four burners, and I had backed Spock right out of the franchise.
In an early draft, Carol Marcus's role was taken by Janet Wallace, a different scientist Old Flame of Kirk's who had appeared in the TOS episode "The Deadly Years".