History Film / HotTubTimeMachine

* SpiritualSuccessor: From the TimeTravel, to the MisterSandmanSequence, to standing up to the bully and his toadies, to the [[ALittleSomethingWeCallRockAndRoll A Little Something We Call Hip-Hop]] scene, to the search for the AppliedPhlebotinum in order to get back, to the minor part played by Creator/CrispinGlover, this is ''Film/BackToTheFuture1'' for a new generation... or more like the same generation, but inverted.

* ForWantOfANail: The bar bet turns into a nightmare for Lou. The squirrel that was vomited on in an earlier scene changes the history of the NFL playoff game as it disrupts John Elway's pass on the field.

--> '''Adam:''' By the way, where does it say in the fucking Friendship Handbook that you are the only one who's allowed any fucking problems?
--> '''Lou:''' I forgot that it says in the Asshole Handbook that you can just fuck over your friends whenever you want!
--> '''Adam:''' Actually, it would say that in the Asshole Handbook if it was, like, guidelines for being an asshole, that's what it would say.

* BadFuture: Inverted, as the movie starts out in one. Nick works a dead-end job of cleaning dogs' anuses, Jacob [[BasementDweller lives in his uncle's basement]], and Lou's life is so bad, he attempts suicide. [[spoiler:In the new timeline at the end of the film, Nick lives his dream of being a musician, Lou becomes a billionaire by exploiting what he knew would happen after the '80s, Jacob lives with his rich father and Adam winds up with the woman he loves.]]

* CallingTheOldManOut: After Jacob sees [[spoiler:Lou is having sex with Kelly,]] he becomes completely flabbergasted that [[spoiler:this makes Lou his father,]] which Jacob sees as a sort of MoralEventHorizon.
-->'''Jacob''': "I always knew there was a reason I hated you!"

* AndStarring: The film buries an "and introducing William Zabka"[[note]]as Rick, though not noted[[/note]] after the cast list in the end crawl, presumably as a joke [[note]]Zabka's first of many screen roles was in the original 1984 version of ''Film/TheKarateKid'', slightly before the 1986 setting of this film[[/note]].

* SpiritualSuccessor: From the TimeTravel, to the MisterSandmanSequence, to standing up to the bully and his toadies, to the [[ALittleSomethingWeCallRockAndRoll A Little Something We Call Hip-Hop]] scene, to the search for the AppliedPhlebotinum in order to get back, to the minor part played by Creator/CrispinGlover, this is ''Film/BackToTheFuture'' for a new generation... or more like the same generation, but inverted.

* DelayedRippleEffect: Obviously as an homage to ''Film/BackToTheFuture'', Jacob starts to flicker and disappear as his parents' mating session is interrupted.

* DoubleStandardAbuseFemaleOnMale: Jenny stabbing Adam in the eye for breaking up with her is treated fairly trivially. Despite knowing what she did Adam and his friends still think he shouldn't have broken up with her and when Adam does get angry at her it’s for her hypocrisy for [[spoiler:getting mad at him when she was going to break up with him anyway]] not for being violent in the first place. Not once does anyone comment that stabbing someone in the eye is a despicable, abusive act.

* TheFriendNobodyLikes: Lou is this for the gang. His nonstop obnoxious {{Jerkass}} streak and overall sociopathic self-destructive tendencies that often put him and his friends in peril lead the rest of the gang to despise him greatly despite still choosing to hang around him. Even his own son and wife as seen in the sequel if Lou continued his ways found him to be a "virus" and want nothing to do with him.

** Lou. He's very obnoxious and rude but that's justified because he's a {{Manchild}}. He undergoes some CharacterDevelopment and he finally lets go of his friends and accepts them for who they are, making him a JerkWithAHeartOfGold.

** Blaine and his friends repeatedly gang-up on people (namely Lou) for [[ItAmusedMe their own amusement]]. They do have a PetTheDog moment of [[spoiler:helping out the bellhop as the latter loses his arm]].

** Blaine and his friends are a GangOfBullies who repeatedly assault and humiliate people (namely Lou) for no good reason. They do have a PetTheDog moment of [[spoiler:helping out the bellhop as the latter loses his arm]].

* GivingRadioToTheRomans: PlayedForLaughs - Lou decides to stay in the 1980s instead of returning to his present, and spends the intervening time becoming a billionaire by getting in on the ground floor of every important innovation since between then and now.

* HairTodayGoneTomorrow: Lou is as bald as the actor who plays him - Rob Corddry. When they first arrive in the past he goes to take a piss and catches sight of himself in the mirror. He's so in awe of his own former glory that he doesn't even stop pissing as he turns to stare in dumbfounded wonder.

* InterruptedIntimacy: Adam, Nick and Jacob walk in on Lou having sex with Adam's sister, meaning Jacob [[PrimalScene witnesses his]] [[{{Squick}} own conception]]...sort of. When he tries to attack Lou, he disappears. CoitusUninterruptus has to ensue to ensure Jacob lives.

* JerkAss: Lou. He's very obnoxious and rude but that's justified because he's a ManChild. He undergoes some CharacterDevelopment and he finally lets go of his friends and accepts them for who they are, making him a JerkWithAHeartOfGold.

* TimeyWimeyBall: The film is really inconsistent with its time travel mechanics. Four friends travel back to one day in 1986 and hijack their younger bodies, so everyone sees them as their younger selves. Except one of the friends - Jacob - wasn't born yet and looks the same in the past as he did in the present, and can also interact with the past, but whenever something happens that might possibly stop his conception he flickers out temporarily. Initially the friends, fearing the ButterflyOfDoom, try to enact a StableTimeLoop by making sure the big events they remember from that night still happen, but then they change their minds and try to make sure the night goes better the second time around. Some of the big events they remember still happen no matter what they do, but no in the way they remember them. Other events they really do alter. Meanwhile they directly or indirectly cause a couple of historical changes. [[spoiler:In the end Lou decides to stay behind and use his knowledge of the future to greatly improve his and everyone's lives. When the other three friends get back they all have much better lives but do not remember them]].
* TitleDrop: "It must be some kind of...Hot Tub Time Machine." Craig Robinson lampshades the trope by delivering a deadpan AsideGlance to the camera immediately after saying the line.

%% * PlayingGertrude: Kelly and April in the future. Kelly especially because at least they tried to make April look older.

** A poster for ''Film/{{Rambo}} 3'' is seen on Blane's bedroom wall, despite the film being set over two years before ''Rambo 3'' was released in May of 1988.

* HighConcept: "Must be some sort of... [[TitleDrop hot tub time machine.]]"

* FourManBand: Adam is the OnlySaneMan, Jacob is the SmartGuy, Lou is the ButtMonkey and Nick is the CasanovaWannabe .

* AsLongAsItSoundsForeign: Invoked. When pretending to be a Russian spy, Nick brandishes the can of Chernobly like it was a bomb and repeatedly shouts "Dosvedanya!", which is Russian for "Goodbye" or "Farewell."

** Downplayed with the "What color is Michael Jackson?" bit. By 1986, Jackson's vitiligo-enduced skin lightening was just starting to become obvious to the public. Though he would retain a mostly tan complexion until the early 1990s.

* AndStarring: The film buries an "and introducing William Zabka"[[note]]as Rick, though not noted[[/note]] after the cast list in the end crawl, presumably as a joke [[note]]Zabka's first of many screen roles was in the original ''Film/KarateKid'', slightly before the 1986 setting of this film[[/note]].

The last film to be distributed by Creator/{{MGM}} before its bankruptcy and reorganization as a pure producer and co-funder as well as the last film credited by Creator/UnitedArtists until Annapurna and MGM revived the brand in 2019.
A sequel was released on February 20, 2015, and takes place 10 years in the future.