Gillian: [sarcastic] Don't tell me; you're from outer space. Kirk: No, I'm from Iowa. I only work in outer space.
The One WithThe Whales.Kirk is prepared to face the consequences of his actions in the previous movie, but a powerful alien probe is making its way to Earth (yes, another one), wreaking havoc with the environment and shutting down anything with power. Deducing that the probe is searching for humpback whales, which are extinct in the twenty-third century, Kirk and crew use a Klingon Bird-Of-Prey they stole in the last film to Time Travel to The Eighties to retrieve some and save Earth. Hilarity Ensues. Instead of the traditional Space Opera, this movie is an outright comedy. It even lacks a villain, outside of the whale probe and a whaler boat.The wild success of this movie was proof to Paramount that Star Trek can survive as an expanded franchise, and gave Gene Roddenberry the opportunity to create a new series, Star Trek: The Next Generation.
In a more traditional application of this trope, it's often claimed that there isn't a single weapon fired in the movie. This isn't really correct, as there are two actual weapons firings (Kirk using his phaser to weld a door shut, and the whalers trying to harpoon George and Gracie) and one attempted (Chekov trying to stun the interrogation officers). This is likely a mix-up with a real fact, namely that this is the only Star Trek film with a body count of zero.
Came Back Wrong: It's implied that maybe we didn't quite get all of Spock back at the end of the previous movie, that there's a certain... something missing. He gets better by the end though. Death apparently isn't something you can just get over straight away.
Cat Folk: The Caitian admiral at Star Fleet headquarters.
Changed My Jumper: The short notice for this particular mission results in the crew arriving in San Francisco in their 23rd Century clothes. As it's San Francisco, they don't look that out of place. Truth in Television — they had unknown crew walk around San Francisco in the outfits for a week before shooting started, and got no comments whatsoever. See City of Weirdos.
The Klingon Bird-of-Prey, which was just the enemy ship and later a means of escaping from the exploding Genesis Planet in the previous film, ends up being a vital part of this film's storyline thanks to its ability to cloak and land.
Kirk's glasses are an unusual case of this; from the perspective of the audience and Kirk himself, this is the last time the glasses are seen. However, 298 years down the line, they're going to be very important once again.
City of Weirdos: Most people are willing to accept the slightly out-of-touch Spock as a harmless stoner, even as he does weird things like jump into the whale tank...until he says things about the whales that he shouldn't be able to know. Truth in Television as anyone who lives in San Francisco could tell you.
Crazy Enough to Work: Even though it's the crew of the mighty Enterprise we're talking about, the whole "get some whales from back in time" thing did sound pretty ridiculous. McCoy lampshades this, to which Kirk simply responds that he should offer a better plan if he can think of one.
Death Amnesia: Played with. Spock never says he can't remember what dying and coming back was like, but it was such an alien experience that he can't discuss it in terms anyone else will understand.
Dedication: To the crew of the Challenger at the beginning of the film.
Defictionalization: There are no less than three formulas for transparent aluminum in reality.
Did Not Do the Research: In-Universe, the crew, knowing only the broad strokes of the sociopolitical environment of the late twentieth century United States, failed to realize that putting Chekov, a Russian, on the ground looking for "nuclear wessels" was a bad idea.
McCoy: This woman has acute post-prandial upper-abdominal distension! Kirk: What did you say she had? McCoy: Cramps.
Every Helicopter Is A Huey: Sulu mentions he trained on Hueys at the Academy as a hobby to a helicopter pilot (though the pilot probably didn't know he meant Starfleet Academy). The Novelization expands on it.
Fish Out of Temporal Water: The whole premise of the film, figuratively and almost literally, thanks to the cetaceans out of temporal water.
Gaia's Lament: Whales are extinct in the 23rd century.
"Get Out of Jail Free" Card: Starfleet can't really punish Kirk and crew too much just after they saved the world, can they?
Inferred Holocaust: We never do find out what happened to the crew of the Saratoga, or the other ships that the probe disabled en route to Earth. Who knows how many, if any, survivors there were on the ships where the life support was barely functioning, and the crew had to watch their emergency power run lower...and lower. Word Of God, however, Jossed the idea that they died, and the novelization mentions in passing that the captain of the Saratoga managed to save her crew.
Large Ham: John Schuck as the Klingon Hambassador makes Shatner look positively subdued.
"You pompous ass!"
Lighter and Softer: This is pretty much the most lighthearted Trek film there is.
Mister Sandman Sequence: An interesting version, seeing as it was applied to what was then the real-life present day.
Modern Humans are Morons: Kirk states to his crew before exploring 20th Century San Fransisco that "this is an extremely primitive and paranoid culture" and believes that no one pays attention to you in the contemporary age "unless you swear every other word." Bones is shocked to find a woman in a hospital on dialysis, asking if this is The Dark Ages.
Mythology Gag: The Bridge Computer Sound Effects from The Original Series can clearly be heard in the background as Kirk says "Let's see what she's got".
Name's the Same: "Sir! Ve have found the nuclear wessels! And Admiral....it is the Enterprise!
Oh Crap: The whaler upon seeing the Bird-of-Prey decloak. Not only could the entire whaler fit in the Bird-of-Prey's torpedo launcher, but these are late 20th century humans. They have never seen an alien (or even human) starship of any kind before.
Precision F-Strike: Lampshaded. "Are you sure it isn't time for a colorful metaphor?"
Reality Subtext: At the end of the movie, when the crew are speculating what ship they're going to get:
Sulu: I'm counting on Excelsior.
Scotty:Excelsior? Why in God's name would you want that bucket of bolts?
This is a twofer: Harve Bennett, producer and writer of the film, had initially wanted the crew to end up commanding the USS Excelsior (which had been seen in the previous film) but was overruled; and Sulu himself ends up as captain of the Excelsiortwo films later.
Sarcastic Confession: Kirk flat out tells Gillian exactly who he is and where he comes from over dinner. Subverted in that Kirk tells her with utter conviction and she naturally thinks he's full of shit.
Only an example, though, if it's taken too literally. The intended Aesop is more along the lines of "you don't know what you've got till it's gone", specifically the permanence of extinction.
Also, don't play your music too loud on the bus or you will wind up nerve pinched.
Scotty and transparent aluminum. In the novelization, the engineer he sells the formula to is the one who introduce[d/s] it to the world.
Scotty: "How do we know he didn't invent the thing?"
In the Novelization, Scotty recognizes the name Dr. Nichols, and immediately pegs as him being the actual inventor of transparent aluminum, and actually invokes the Trope, saying that it could be necessary to tell him about how it could be done. Regardless, it could cyclical in that Scotty recognizes Nichols as the inventor - and might have realized that he's supposed to make him the inventor.
When Kirk sells his glasses at a pawn shop.
Spock: Admiral, weren't those a gift from Dr. McCoy?
Kirk: And they will be again. That's the beauty of it.
No one checks to see if removing Gillian from the timeline will change anything historic. Dispite her insistance "I have nobody here", no one considers the possibility that any future actions of her's could be important.
Throw It In: They actually had Nichols and Koenig asking real San Franciscans where the nuclear submaine in Alameda was. The police officers staring suspiciously at the pair was a real cop who didn't know what was going on. The woman who answers, "Ooh, I don't know. I think they're in Alameda", had to be chased down to sign a release form for providing such a hysterical line in response to their queries.
Time Travelers Are Spies: Chekov and Uhura, big time. Though it might have gone better if one of them wasn't Russian.
Totally Radical: Kirk doesn't quite have a grasp on 1986 idioms. Nor does Spock.
Kirk: And a double dumbass on you!
Unishment: When Kirk is demoted back to the Captaincy of a starship... which is what he wanted all along anyway.
Weld The Lock: Kirk uses a phaser to melt the lock on a door he locked some 20th-century medstaff in. This, incidentally, is the only time a phaser is fired throughout the entire movie, showing just how Lighter and SofterIV is compared to pretty much all the other films.
We Will Have Perfect Health in the Future: Demonstrated when McCoy, visiting a twentieth century hospital, is horrified that a woman is undergoing kidney dialysis. "Dialysis? What is this, the Dark Ages?" He gives her a pill, and minutes later, doctors are dumbfounded by her miraculous recovery as she grows a new kidney.