[[caption-width-right:210:"Forget the [[TimePolice Temporal]] [[AlienNonInterferenceClause Prime Directive]]. From now on, we follow the RuleOfFunny!"]]

->'''Gillian:''' ''[sarcastic]'' Don't tell me; you're from outer space.\\
'''Kirk:''' No, I'm from Iowa. I only ''work'' in outer space.

''Star Trek IV: The Voyage Home'' is the fourth movie in the ''Franchise/StarTrek'' film series, released in 1986.

This is "TheOneWith [[SpaceWhaleAesop The Whales]]".

Kirk is prepared to face the consequences of his actions in the [[Film/StarTrekIIITheSearchForSpock previous movie]], but a powerful alien probe is making its way to Earth ([[Film/StarTrekTheMotionPicture 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 TimeTravel to UsefulNotes/SanFrancisco in TheEighties, where they hope to retrieve some and save Earth. HilarityEnsues. Instead of the traditional SpaceOpera, this movie is an outright comedy. It even lacks a villain, outside of the whale probe and a whaler boat.

''Star Trek IV'' is often considered a RealLife example of when ''Star Trek'' can indeed be ActuallyPrettyFunny. The wild success of this movie (it was the most financially successful ''Trek'' film until the [[Film/StarTrek 2009 reboot]]) was proof to Paramount that ''Franchise/StarTrek'' could survive as an [[ExpandedUniverse expanded franchise]].

Not only did it greenlight more films, but it gave GeneRoddenberry the opportunity to create a brand new TV series, ''Series/StarTrekTheNextGeneration''.

!!Tropes seen in ''The Voyage Home'' include:

* AcronymConfusion:
-->'''Kirk:''' Oh, him? He's harmless. Part of the free speech movement at Berkeley in the sixties. I think he did a little too much LDS[[note]]This acronym refers to the Church of Jesus Christ of Latter Day Saints, aka the Mormons[[/note]].\\
'''Gillian:''' L ''D'' S?
* ActingUnnatural: Kirk tells his bridge officers, standing around in the streets of 1980s San Francisco, to "break up, you look like a cadet review." Cue entirely unconvincing attempt by the Starfleet officers to look inconspicuous and casual.
* AdamAndEvePlot: With the whales brought to the future.
* AliceAllusion: Kirk's greeting to Gillian as she's beamed aboard the Klingon ship. "Hello Alice, welcome to Wonderland".
* ArcWords: "How do you feel?" Later, "I feel fine."
* ArmorPiercingQuestion:
** By Sarek, in response to the Klingon ambassador's overblown accusations against Kirk.
--->'''Ambassador:''' We have the right to preserve our race!\\
'''Sarek:''' You have the right to commit murder?
** Also, the above-mentioned "How do you feel?"
* ArsonMurderAndLifesaving: Stealing Starships, Disobeying Orders, And Saving The World.
* ArtisticLicenseMedicine: When Mc[==]Coy is arguing with the 20th century doctor about the merits of a fundoscopic examination on Chekov while he is in a coma. The argument implies it will involve the use of a medical drill. In reality a fundoscopic examination is a routine part of a medical checkup where the doctor shines a light in the patient's eye and examines it with an ophthalmoscope.
* AssInAmbassador: The Klingon ambassador, to be specific. As he and his party leave, an unseen heckler actually calls him a pompous ass.
* AwLookTheyReallyDoLoveEachOther: Spock and Sarek have a moment. After a brief icy exchange where Spock says (somewhat backhandedly) that he appreciated his father making the effort to attend the trial, Sarek countered softly with "it was no effort, you are my son". Probably as close to a gooey moment as you would get between a Vulcan father and son.
* BavarianFireDrill: Kirk, [=McCoy=], and Gillian getting into the hospital to rescue Chekov. See ExpospeakGag below.
* BigDamnHeroes: Kirk and the crew seem too late stop the whalers, [[spoiler:only to have the launched harpoon suddenly hit something invisible. Then Kirk's ship decloaks and reveals it had gotten in place to block the shot in time]].
* BigDumbObject: The "whale probe". Presumably to [[GreenAesop to make a point]] about it being as thoughtlessly destructive to humanity as humanity supposedly is to whales.
* BlackBossLady: Audiences applauded when Madge Sinclair appeared as the (unnamed) Captain of the ''Saratoga'' at the beginning of the film.
* BlueAndOrangeMorality: The probe, which is completely inscrutable.
* BluntMetaphorsTrauma: {{Justified|Trope}}, as Spock has an incomplete grasp on life after being brought {{back from the dead}}.
--->'''Kirk:''' If we play our cards right, we may be able to find out when those whales are being released.\\
'''Spock:''' How will playing cards help?
--->'''Dr. Taylor:''' Are you sure you won't change your mind?\\
'''Spock:''' Is there something wrong with the one I have?
* BookEnds: Kirk refers to the others as 'My friends' when they commit themselves to help Spock in ''Film/StarTrekIIITheSearchForSpock'' ("My friends, Dr [=McCoy=] and I have to do this, the rest of you don't") and again after the resulting trial in this film's ending ("My friends, We've come home.")
* BrakeAngrily: Gillian slams the brakes on her truck after Spock declares that [[spoiler:Gracie is pregnant]].
* BreatherEpisode: According to WordOfGod.
* CameBackWrong: 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.
* CassandraTruth: After failing to come up with a cover story she'll accept, Kirk flat out tells Gillian exactly who he is and where he comes from over dinner. She naturally thinks he's full of shit.
* CatFolk: The Caitian admiral at Star Fleet headquarters.
* CatchPhrase:
** "Hello, Computer."
** Nuclear wessels!
** Double dumb-ass on you!
** Spock's awkward and inappropriate usage of the phrase, "[[RunningGag the hell]]".
--->'''Spock:''' They like you very much, but they are not the hell your whales.\\
'''Dr. Gillian Taylor:''' I suppose they told you that, huh?\\
'''Spock:''' The hell they did.
* ChangedMyJumper: The short notice for this particular mission results in the crew arriving in San Francisco in their 23rd century SpaceClothes. As it's UsefulNotes/SanFrancisco, they don't look that out of place. TruthInTelevision -- they had unknown crew walk around San Francisco in the outfits for a week before shooting started, and got no comments whatsoever. See CityOfWeirdos.
* ChekhovsGun:
** 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.
* CityOfWeirdos: Most people are willing to accept the slightly out-of-touch Spock as a [[TheStoner 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. TruthInTelevision as anyone who lives in San Francisco could tell you.
* ClusterFBomb: Cluster "The Hell" Bomb
* CloudCuckooLander: Spock, but in all fairness he is still recovering from being dead.
* ComplainingAboutRescuesTheyDontLike: Spock initially feels that his shipmates, being illogical humans as they are, made a huge mistake by sacrificing their careers, the Enterprise and Kirk's son David just so they could have him back.
* ContinuityNod: Kirk mentions that they've done slingshot maneuvers around the sun before, which they first did in the episode "[[Recap/StarTrekS1E19TomorrowIsYesterday Tomorrow Is Yesterday]]."
* CrapsackOnlyByComparison: How the crew of the Enterprise see TheEighties, largely PlayedForLaughs. Kirk warns the crew that they're dealing with a "primitive and paranoid culture", one character remarks (on a newspaper headling concerning nuclear arms talks stalling) that "it's a wonder these people ever got out of the 20th century" and [=McCoy=] shows characteristic disdain for 20th-century medical practices when [[spoiler:Chekhov has an accident and ends up critically injured in hospital]].
* CrazyEnoughToWork: Even though it's the [[BadassCrew 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 if [=McCoy=] has a better plan, he should speak up. The film is also nice enough to explain why several saner sounding plans wouldn't work.
* CriticalResearchFailure: InUniverse. 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.
* CriticalStaffingShortage: The stolen Klingon bird of prey is manned only by the Enterprise command crew, half of what it should have.
* CurbStompBattle: Well, there's no actual ''battle'', but the Probe gives V'ger a run for its money to completely decimate the entire Federation and Earth ships and defenses. It does this as a mere side effect of transmitting its signal and is otherwise [[ObliviouslyEvil completely oblivious to the damage it causes.]]
* DamageControl: Kirk asks when they can get their captured Bird-of-Prey under way, Scotty quips, "Damage control is easy; reading Klingon, that's hard."
* DeathAmnesia: Played with. Spock never says he can't remember what dying and coming back was like. He states that he can't explain it without the other person having a common frame of reference, meaning:
-->'''Bones:''' You mean I have to ''die'' to discuss your insights on death?!
* {{Dedication}}: To the crew of the ''Challenger'' at the beginning of the film.
* DemotedToExtra: Saavik, who was a major character in ''[[Film/StarTrekIITheWrathOfKhan The Wrath of Khan]]'' and ''[[Film/StarTrekIIITheSearchForSpock The Search for Spock]]'', made a brief appearance in only one scene in this movie, and then was never seen again.
* DontCallMeSir: Due to Spock's mental retraining, he insists on calling Kirk "Admiral". Kirk is nonplussed and keeps insisting that Spock used to call him "Jim".
* DudleyDoRightStopsToHelp: [=McCoy=] helping the woman on dialysis during their rescue of Chekov. Admittedly, the "stop" didn't take more time than it took to give her a couple of pills, but it still (a) potentially draws attention to what's supposed to be a covert mission and (b) has the possibility of changing history.
* TheEighties: the time period the crew travel back to is fairly unambiguously this.
* EmergencyRefuelling: After the crew use the Klingon Bird of Prey to travel back in time, the dilithium crystals in the Bird of Prey start disintegrating due to the amount of effort required to travel back in time. This leads to a subplot where Uhura and Chekhov have to find a nuclear vessel, collect high energy photons from a nuclear fission reaction and use those to recrystalise the dilithium crystals.
* EverybodyLives: The only Trek film that can boast this.
* ExactWords: Spock's plan.
-->'''Spock:''' We could try to find some humpback whales.\\
'''[=McCoy=]:''' But you said there aren't any, except on ''Earth of the past.''\\
'''Spock:''' That is correct, Doctor.
* ExpospeakGag:
-->'''[=McCoy=]:''' This woman has acute post-prandial upper-abdominal distension!\\
'''Kirk:''' What did you say she had?\\
'''[=McCoy=]:''' Cramps.
* ExtyYearsFromNow: From 2286 to 1986, the crew travel back exactly 300 years in to the past.
* EveryHelicopterIsAHuey: Sulu tells a helicopter pilot that he trained on Hueys at the Academy, as a hobby (though the pilot probably didn't know he meant ''Starfleet'' Academy). The {{Novelization}} expands on it.
* FacePalm: Kirk's reaction to Spock diving into the whale tank without warning him.
* {{Foreshadowing}}: The Klingon ambassador mentions attempts to negotiate a peace treaty, and that there would be no peace whilst Kirk lived. This may or may not have been intentional, but it's picked up as the central theme of the plot in the sixth movie--where, interestingly enough, the same character (and actor) is one of the first to applaud Kirk and the ''Enterprise'' crew when they prevent the sabotage of the eventual Federation/Klingon treaty.
* FishOutOfTemporalWater: The whole premise of the film, figuratively and almost literally, thanks to the cetaceans out of temporal water.
* GaiasLament: Whales are extinct in the 23rd century. The probe tries to communicate until something responds... if nothing responds, it never stops trying. (It just so happens that its communication drains Starfleet power supplies and screws up's Earth's surface weather...) The designers of the probe were callous and uncaring what side-effects this would have, just as the 20th century humans were callous and uncaring regarding the plight of the whales-- at least that's the idea.
* GetOutOfJailFreeCard: Starfleet can't really punish Kirk and crew ''too much'' just after they saved the world, can they?
* GettingCrapPastTheRadar: Multiple instances of profanity in a PG-rated movie, including FlippingTheBird, some even {{Lampshaded}}.
* GoodOldWays: A perfect example of the ways in which Bones ''subverts'' this trope. See WeWillHavePerfectHealthInTheFuture.
* TheGreatPoliticsMessUp: The probe is causing bad weather in 23rd century Leningrad, although the oblast (province/state) still retains that name.
* GreenAesop: "To hunt a species to extinction is not logical."
-->'''Gillian:''' Whoever said the human race was logical?
* LargeHam: John Schuck as the Klingon ''Ham''bassador makes Shatner look positively subdued.
-->"Behold, the quintessential devil himself: James T. Kirk, renegade and terrorist!"
-->"Starfleet regulations, that's outRAGEOUS!!!"
* KickedUpstairs: [[InvertedTrope Inverted]]: Kirk has violated orders to save the world. They "punish" him by taking away his cushy desk job and demoting him to a "mere" starship captain. So Star Fleet gets what it wants (a public punishment to demonstrate they don't tolerate such behavior, not to mention their best captain back in the field) and Kirk gets what he wants (the Enterprise).
* LaserGuidedKarma: Kirk and Company survived to save the world because they were off-planet rescuing Spock when the probe arrived.
* LighterAndSofter: This is pretty much the most lighthearted ''Trek'' film there is.
* LiteralMinded: Chekov during the interrogation, much to the frustration of his interrogator. A possible case of ObfuscatingStupidity.
* MagicalSecurityCam: When the Klingon Ambassador shows the Council footage of the ''Enterprise'' blowing up with Kruge's crew aboard, it's the exact footage from the previous film. The bit with Kruge's crew on the bridge has an overlay added to suggest that it was somehow recorded and transmitted by one of the crew before they died; no effort is made to explain who recorded the external shots of the ship going down in flames.
* MeaningfulRename: The crew have dubbed their stolen Klingon ship the ''[[Film/MutinyOnTheBounty HMS Bounty]]''.
* MistakenForSpies: Chekov. An interesting example as Chekov's behavior eventually leads one of his interrogators to suspect he's something like an escaped mental patient rather than a Soviet spy.
* MisterSandmanSequence: An interesting version, seeing as it was applied to what was then the real-life present day.
* MoodWhiplash: When Gillian starts showing videos of actual whale disassembling. In theaters, the audiences often got ''very'' quiet at this point.
* {{Mundanization}}: They've triumphed many times in space, but how well do they do on present-day Earth?
* MythologyGag: 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".
* NamesTheSame: An in-universe example. "Sir! Ve have found the nuclear wessels! And Admiral....it is the ''Enterprise''!"
* NiceJobBreakingItHero: Everyone's reaction to the Humans of the past for hunting the Humpback to extinction.
* NoAntagonist: Even the probe is just trying to find out what happened to their friends on Earth.
* NoEndorHolocaust: 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. However, one captain mentions attempting to jury-rig a solar energy collector to restore power to life support, and Starfleet crews in general are expected to be resourceful. WordOfGod {{Jossed}} the idea that they died, and the novelization mentions in passing that the captain of the ''Saratoga'' managed to save her crew.
* NoOneGetsLeftBehind: When Chekov is at the mercy of 20th Century medicine, Bones insists on going to save him. Spock backs him up. When asked if it's the logical thing to do, he admits that it is not. It is, however, the ''human'' thing to do.
* NotThisOneThatOne: A notable inversion/subversion at the end: The crew arrives at Space Dock to take charge of their new ship. The crew argues about which ship they will get. Dr. [=McCoy=] trusts the bureaucrats to give them a freighter, while Mr. Sulu opines he would like the Excelsior. Scotty of course scoffs at Mr. Sulu, asking why he would want that "bucket of bolts". Their shuttle starts its approach on the shiny new Excelsior... then flies over it to reveal the smaller ship hiding behind it: the Enterprise-A.
* ObfuscatingStupidity: How Chekov deals with his (brief) interrogation by the FBI could be interpreted to be this instead of simple FishOutOfTemporalWater naivety. You decide.
* OhCrap: The whaler's crew 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. Needless to say they scurry away as fast as they are able to turn the ship around.
* OnceMoreWithClarity: During the time travel sequence, the lines spoken by the crew during the sequence are spoken later on.
* OpenMouthInsertFoot: Gillian's co-worker Bob. All the time.
* PhotographicMemory: Gillian Taylor mentions that she has one -- "I ''see'' words!" -- but it comes into play only once, during Spock's TimeTravelTenseTrouble.
* PrecisionFStrike: Kirk advises Spock to blend in by "swearing every other word". While he has difficulty at first he finally grasps it, and, in perhaps a running gag, Spock has at least one in parts 5 and 6 as well.
-->'''Spock:''' Are you sure it isn't time for a colorful metaphor?
* PromotionNotPunishment: At the end, Kirk actually experiences a subversion. After [[Film/StarTrekIIITheSearchForSpock stealing the Enterprise and subsequently blowing it up]] in the [[ArsonMurderAndLifesaving process of stopping the Earth from being destroyed and saving the humpbacked whales from extinction]], he and his bunch manage to almost completely duck the surefire court-martialing and dismissal from Starfleet. Instead, Kirk is demoted from Admiral back down to Captain, [[{{Unishment}} a role both he and his superiors prefer him in.]]
* TheQuincyPunk: Kirk and Spock encounter such a punk on a bus in 1980s San Francisco. When he refuses to turn down the loud punk rock music he is playing, Spock nerve pinches him into silence, and everyone else on the bus applauds.
* RapidFireTyping: Scotty goes from not even understanding the concept of a computer without voice commands to apparently being able type 3 million words per minute. Also combines with HollywoodHacking -- the action on the computer's screen doesn't even remotely synch with his keystrokes.
* RealLifeWritesThePlot: There was actually a scene in the script for Sulu to steal the helicopter by at first taking the pilot away from the helicopter and then take a running leap into the helicopter while he was away. Unfortunately/fortunately, George Takei had taken place in a marathon and was too sore to do the scene, and with only few days to complete the film the scene was scrapped
* RefugeInAudacity: Chekov, in obviously Russian accent, going around the streets asking about "nuclear wessels" and ''getting away with it.'' Doesn't help him when he actually gets found on board one, however.
* ReplacementGoldfish: The Enterprise NCC-1701-A for the Enterprise NCC-1701, beginning a ''Franchise/StarTrek'' tradition.
* RogueAgent: The Klingon Ambassador tries painting Captain Kirk as this, in an attempt to get him extradited.
* ScrewTheRulesItsTheApocalypse: In that the crew are not averse to breaking the law in the 20th century in order to save the Earth in the 23rd, to wit:
** Scotty and [=McCoy=] obtaining a supply of Plexiglass (to house the whales) using fraud and bribery;
*** They most likely did not steal it, but traded the plant manager of the factory it was made the formula for transparent aluminum in exchange for the Plexiglass.
** Chekhov and Uhura illegally boarding a US Navy vessel and stealing power (for the purposes of recrystallizing the dilithium matrix in the warp drive allowing them to get home); then Kirk and co. removing a criminal suspect under arrest (Chekhov, who gets captured in the process) from police custody.
* SequelHook: The crew is absolved of all criminal charges and are given a new ship, a virtually identical Constitution class USS Enterprise: NCC-1701-'''A'''. The adventures of this ship are continued in ''Film/StarTrekVTheFinalFrontier'' and ''Film/StarTrekVITheUndiscoveredCountry'', but it also paved the way for the introduction of the [[Series/StarTrekTheNextGeneration Galaxy Class USS Enterprise]] NCC-1701-'''D'''.
* ShoutOut:
** According to WordOfGod, the probe is modeled after [[Literature/RendezvousWithRama Rama]].
** The Whales are named after [[Creator/GeorgeBurns George Burns and Gracie Allen]].
** Scotty refers to the ''Excelsior'' as a "[[Film/TheEmpireStrikesBack bucket of bolts]]."
* SnapBack: [[spoiler:After all the trial and tribulation the crew goes through in the last three films, they all end up back where they started: on the bridge of the ''Enterprise'' ready for a new adventure]].
* SirSwearsALot:
** Kirk tries to be this, with middling success. "''Double'' dumbass on you!"
** Spock tries even harder, with less success.
* SophisticatedAsHell: A major source of humor from Spock.
* SpaceWhaleAesop: TropeNamer. Don't hunt whales to extinction or an alien probe will come to destroy us all!
** 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.
** Just because somebody claims to have come from the future to save the Earth doesn't mean they're crazy or trying to scam you. They're only ''almost certainly'' crazy or trying to scam you.
* SpottingTheThread:
--> '''Security Guard:''' How's the patient, Doctor?\\
'''Kirk:''' He's going to make it.\\
'''Guard:''' He? They went in with a she!\\
'''Kirk:''' [[LampshadeHanging One little mistake...]] ''[runs]''
* StableTimeLoop: All over the damn place.
** 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, and Scotty discusses the trope specifically when [=McCoy=] calls him on it.
--->'''Scotty:''' "How do we know he didn't invent the thing?"
*** In the {{Novelization}}, Scotty practically fanboys over the engineer, Marcus Nichols, when they are introduced, because Scotty recognizes Nichols' name as that of the inventor of transparent aluminum; Scotty hints that it might be Scotty and Bones' job to actually ''tell'' him about it.
*** Nichols says himself it will take ''years'' to figure out the matrix, so they aren't even giving him the formula - just pushing him in the right direction.
** 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. Despite her insistence that "I have nobody here", no one considers the possibility that any future actions of hers could be important.
*** In the ExpandedUniverse, it's explained that this is actually standard Federation policy towards people from the past that wind up in the "present". If their removal from the timeline ''doesn't'' cause catastrophic changes, they're supposed to stay rather than risk polluting the timeline by going back with knowledge of the future. Also came up in the Original Series episode "[[Recap/StarTrekS1E19TomorrowIsYesterday Tomorrow is Yesterday]]", where Kirk ''would've'' taken [=USAF=] Cptn. John Christopher back to the 23rd century, if not for the fact that his yet-to-be-conceived son was commander of the first successful manned flight to Saturn.
* StupidestThingIveEverHeard: During the FBI's interrogation of Chekov:
-->'''Agent #1:''' What do you think?\\
'''Agent #2:''' He's a Russkie.\\
'''Agent #1:''' That's the stupidest thing I've ever heard in my life. Of ''course'' he's a Russkie, but he's a retard or something.
* SuspiciouslySimilarSubstitute: [[http://memory-alpha.org/wiki/Cartwright Admiral Cartwright]] for [[http://memory-alpha.org/wiki/Harry_Morrow Admiral Morrow]], who appeared in ''Film/StarTrekIIITheSearchForSpock''. The novelization implies Morrow got replaced due to a scandal that erupted from Kirk's actions.
* TimeTravelersAreSpies: Chekov and Uhura, big time. Though it might have gone better if one of them wasn't Russian. In the {{Novelization}}, the fact Uhura is African doesn't help matters.[[note]]Ethiopia's relationship with the USSR, for one.[[/note]]
* TimeTravelRomance: Kirk finds a LoveInterest wherever and whenever he goes, doesn't he?
** Though it's very low-key (especially for Kirk) and doesn't really become much more than some flirting and a hug. Which makes sense considering the character becoming a female scientist was actually a fairly late revision to the script... in prior drafts, the character was a conspiracy theorist [[WhatCouldHaveBeen played by Eddie Murphy]].
* TimeTravelTenseTrouble: Spock of all people screws up here. Nimoy stresses the tense loud and clear, so it wouldn't take eidetic memory to remember it, too.
* TotallyRadical: Kirk doesn't quite have a grasp on 1986 idioms. Nor does Spock.
-->'''Kirk:''' And a double dumbass on ''you''!
* TranquilFury: Sarek is incensed with the Klingon Ambassador's attempted justifications for Commander Kruge's actions in the previous movie. Of course, being a typical Vulcan, Sarek is still reserved about it but his tone and words make it clear what he thinks.
-->'''Sarek:''' Your vessel did destroy U.S.S. Grissom. Your men did kill Kirk's son. Do you deny these events?\\
'''Klingon Ambassador:''' We deny nothing! We have the right to preserve our race!\\
'''Sarek:''' You have the right to commit murder?
* {{Troll}}: Scotty referring to Bones as "his assistant". Scotty's look after implies that he said it just to mess with him. Also one wonders if Spock's misuse of swears didn't become purposeful over time, especially after Kirk criticized him for it.
* TroubleFromThePast: The humans of the past hunted whales to extinction and that turned out to be a bad idea.
* {{Unishment}}: When Kirk is demoted back to the Captaincy of a starship... which is what he wanted all along anyway.
* UnspokenPlanGuarantee: Chekov gives Kirk a simple explanation for how he and Uhura plan to collect high-energy photons from the aircraft carrier ''Enterprise''. It works perfectly--until the transporter fizzles out and Chekov is captured. And critically injured trying to escape. Although it didn't help that he [[TemptingFate tempted fate]] by saying "No one will ever know we were there."
* WeaponsUnderstudies: The nuclear aircraft carrier USS ''Enterprise'' is here played by the non-nuclear USS ''Ranger''. The ''Enterprise's'' reactor area was highly classified and radioactive to the point the film would have been unusable, and even if filming was feasible, she was at sea at the time. If you look closely, you can see several sailors wearing ''Ranger'' insignia.
* WeldTheLock: 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 (successfully--Chekov's attempt fizzles due to a malfunction), showing just how LighterAndSofter ''IV'' is compared to pretty much all the other films.
* WellDoneSonGuy: Spock and Sarek.
* WeWillHavePerfectHealthInTheFuture: 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''.
* WhatWeNowKnowToBeTrue: See WeWillHavePerfectHealthInTheFuture.
* WhamLine:
** [[spoiler:"Gracie is pregnant."]]
** Sarek, with 7 words, dismantles the Klingon ambassador's entire tirade:
--->"You have the right to commit murder?"
** Kirk, when he realizes the only way to save Earth:
--->"Begin computations for time warp."
* WhatYearIsThis: Subverted. All official material indicates they travel back to 1986 (the year the film was released), but Spock determines from the pollution in the atmosphere as being "the latter half of the 20th Century" and Kirk doesn't ask to get more specific than that as it doesn't matter.
* WiperStart: Sulu with the helicopter.
* YouCanSeeThatRight: The two sanitation workers who witness the landing of the cloaked Bird of Prey in Golden Gate Park.
-->"Did you see that?"\\
"No, and neither did you, so shut up."
''My friends....we've come home.''