History Main / TimelineAlteringMacGuffin

* ''Series/DoctorWho'': In [[Recap/DoctorWhoS27E7TheLongGame "The Long Game"]], Adam attempts to leave one of these for himself in the past by recording historical information from 197,988 years in the future on his mother's answering machine. The Doctor finds out. He's not happy. Ironically, Adam himself ends up at risk of becoming one. He has his own brain upgraded in the future, to interface with the computers of the time. Now whenever someone snaps their fingers near him a little port on his forehead opens up. The Doctor mentions that Adam has to lead a quiet life and not draw attention to himself, or he risks [[TheydCutYouUp being dissected]] for the future technology in his skull. At the end of the episode, his mother snaps her fingers while talking to him.
* In ''The Hanged Man'' episode of ''Series/{{Journeyman}}'', a digital camera Dan accidentally left in the early 1980s causes technology to leap far forward when he returns to modern times -- including a family member being wiped from existence because of a "nanotech accident" on the day of his conception.

* In ''Series/LoisAndClark'', after the first time Tempus was defeated, he was left in the past, where he wrote a diary a man would eventually use to become wealthy by investing in oil, plastic and computers. Later, that man's [[TheUnfavorite unfavorite son]] used the diary to blackmail Superman into stealing from the man's other son. According to this VillainOfTheWeek, Tempus was either a man from the future or a fortuneteller good enough to put [[FortuneTeller Nostradamus]] to shame.

* ''Series/TheOuterLimits1995'': In "[[Recap/TheOuterLimits1995S6E17Gettysburg Gettysburg]]", this is attempted but fails. Andy Larouche and Vince Chance get sent back in time to the Battle of Gettysburg. Andy, a Confederate sympathizer, tries to show a book called ''Great Battles of the Civil War'' to Colonel Angus Devine and his men to prevent Pickett's Charge and win the Battle of Gettysburg for the Confederacy. Vince stops him and hides the book in a house Devine and his men occupied. The woman who owns the house later finds the book and is horrified by it. However, she secretly returns it to Vince without asking any questions as she is grateful to him for delivering her baby and saving his life when his umbilical cord became wrapped around his head.

** One of the comics actually referenced the events of "A Piece of the Action", when various representatives were at Admiral Kirk's trial including one from that planet, with the only result being that the representative simply gives it back to [=McCoy=] after saying how he'd left it behind. (They had still kept their original gangster society, though the profits had been invested in things like schools, libraries, and hospitals. What Kirk hadn't anticipated was that as the new boss, they had saved 10% of the take as Kirk's personal cut.)

*** "Future's End" has a 29th Century timeship that was sent back to 1967, although this results in a StableTimeLoop, since the technology boom of the late 20th century turns out to be thanks to the reverse-engineered tech from the timeship. Interestingly, the 29th century technology helps create the "holo-emitter" the Doctor uses for the rest of the series, so the timeship was a Timeline Altering MacGuffin to the 24th Century as well.
*** The final episode leaves the possibility of this trope rather alarmingly dangling overhead. Future Janeway comes back over a decade to bring the crew home, decking out the ship in all kinds of future tech and eventually infecting the Borg Queen with a super nasty future virus. Now, given the Borg's ability to adapt, one can speculate that if they manage to overcome that virus, they would then have adapted to technology and programming the Federation hasn't yet invented. Not only that, but they had already assimilated her shuttle from the future by then, including the armor and the torpedoes. In the ExpandedUniverse novels, specifically ''Literature/StarTrekDestiny'', this comes back to bite them.

* In the ''Series/DoctorWho'' [[AudioPlay/BigFinishDoctorWho audio drama]] "Colditz", it's discovered that their accidental appearance at Colditz Castle goes horribly wrong, and Nazis from the 1960s reveal they got the ''TARDIS''. The twist is that [[spoiler: the Timeline Altering MacGuffin isn't the TARDIS, but a CD Player which leads to the getting to the concept of LASER quicker than they were supposed to, thus having them win the rocket race, making the V missiles more deadly than they were and eventually letting the TARDIS end up in their hands.]]

* ''Series/TheOuterLimits1995'': In "Gettysburg", this is attempted but fails. Andy Larouche and Vince Chance get sent back in time to the Battle of Gettysburg. Andy, a Confederate sympathizer, tries to show a book called ''Great Battles of the Civil War'' to Colonel Angus Devine and his men to prevent Pickett's Charge and win the Battle of Gettysburg for the Confederacy. Vince stops him and hides the book in a house Devine and his men occupied. The woman who owns the house later finds the book and is horrified by it. However, she secretly returns it to Vince without asking any questions as she is grateful to him for delivering her baby and saving his life when his umbilical cord became wrapped around his head.

* In ''ComicBook/TheSandman'', people are digging up a bunch of those from an archaeological dig in Crete. Sadly [[spoiler: some of them are explosive.]]
* In Pre-Crisis ComicBook/{{Superman}} stories, it was well-established that changing the past was impossible. One issue of ''World's Finest,'' however, saw the time travelling villain Chronos acquire the means to "interactively" time travel, so he ''could'' change the past. Fortunately, he never gets the chance. Instead, ComicBook/{{Batman}} gets sent back in time to the night his parents were murdered, tempting him to SetRightWhatOnceWentWrong at the expense of the future he knows. Fortunately, he resists the temptation, and Superman is able to bring him back to the present.

** In the first draft of ''Film/BackToTheFuture'', Marty revealed to 1955 Doc that all his crazy inventions could be cheaply powered with Coca-Cola (ItMakesSenseInContext... [[ItRunsOnNonsensoleum well, almost]]), so when he traveled back to 1985 he actually ended up in an alternate reality where everything was a {{Zeerust}} '50s rendition of the future, with hovering cars and robots everywhere powered by Coca-Cola. The dystopic part? [[ALittleSomethingWeCallRockAndRoll No Rock and Roll!]]

** The former TropeNamer is the Gray's Sports Almanac in ''Film/BackToTheFuturePartII'', which allowed Biff Tannen to become wealthy by placing bets on the outcomes of sporting events when his future self gave it to him in 1955. What makes it work is that the Ripple Effect ensures that the Almanac will recursively update to reflect the changes in outcomes as a result of his prior betting, meaning it'll always be accurate. He then uses the money to become a CorruptCorporateExecutive and ruin the lives of Marty and everyone else in Hill Valley, forcing Marty and Doc to go back in time and stop it.

** In ''Film/StarTrekIVTheVoyageHome'', Scotty teaches the 20th century plastic maker how to make "transparent aluminum", justifying it with the argument, "How do we know ''he'' [the person to whom he gave the formula] wasnae the one who invented it?" (The man himself explicitly points out that working out the details to turn Scotty's sketch into an actual product is going to take years of research.) The original script had Scotty saying that he knows that the manager would eventually go on to "invent" it, therefore giving him the formula created a StableTimeLoop.

* ''LightNovel/FullMetalPanic'': The "Whispered" are privy to "[[BlackBox Black Technology]]" -- devices they should be unable to design for decades or even centuries. It's extended their UsefulNotes/ColdWar clear into the 21st century.

* In ''Literature/TheLeapfroggedConsoleWars'', A Nintendo DS, along with it development kits and design documents, as well as copies of Pokémon Diamond and Pearl and Platinum, are sent to Nintendo at the beginning of 1990. This leads to Nintendo forming an alliance with Apple and ARM to develop the technology to release the DS in 1996, eventually causing the Playstation to bomb.

** The Gray's Sports Almanac in ''Film/BackToTheFuturePartII'' allowed Biff Tannen to become wealthy by placing bets on the outcomes of sporting events when his future self gave it to him in 1955. What makes it work is that the Ripple Effect ensures that the Almanac will recursively update to reflect the changes in outcomes as a result of his prior betting, meaning it'll always be accurate. He then uses the money to become a CorruptCorporateExecutive and ruin the lives of Marty and everyone else in Hill Valley, forcing Marty and Doc to go back in time and stop it.

[[folder:Web Original]]
* A subversion in {{WebOriginal/Driftless Wormhole}} -- a cell phone accidentally taken to a society with {{Dieselpunk}} technology levels would be really useful, but they can't reverse-engineer it. It's so far advanced that they even have trouble gleaning ideas from it that they can use.
[[/folder]]

* The Creator/HarryHarrison novel ''A Rebel in Time'' subverts this. A racist colonel, Wesley [=McCulloch=], goes back in time with Troy Harmon, a black officer, following him, assuming the man is going to give modern weapons to the Army of Virginia and thus help the South win the Civil War. He's confused when Perry instead plans to arm small groups to seize key Union towns. In their final confrontation, the colonel asks why Perry would do this when John Brown tried and failed. Perry's dying words: "Who's John Brown?" Going over his effects later, the colonel realizes that Perry (who barely passed high school and a horrible student of history) just happened to be basing [[CriticalResearchFailure his entire plan]] on the ''one'' book on the Civil War that ''didn't'' mention John Brown or the raid on Harper's Ferry.

* In ''Series/LoisAndClark'', after the first time Tempus was defeated, he was left in the past, where he wrote a diary a man would eventually use to become wealthy by investing in oil, plastic and computers. Later, that man's [[TheUnfavorite unfavorite son]] used the diary to blackmail {{Superman}} into stealing from the man's other son. According to this VillainOfTheWeek, Tempus was either a man from the future or a fortuneteller good enough to put [[FortuneTeller Nostradamus]] to shame.

* ''WesternAnimation/BeastWars'' features the Voyager Disk, which initially only helped Megatron find earth, but was eventually revealed to contain both photos from the planet's [[TimeTravelTenseTrouble present, in the future, which is the past]], and a [[FlingALightIntoTheFuture message from G1 Megatron]] ordering [[TimeTravelTenseTrouble future Decepticons to go into the past to change the present.]] Both were used in attempts to MakeWrongWhatOnceWentRight, with varying degrees of success.

* ''Literature/AConnecticutYankeeInKingArthursCourt'' by Creator/MarkTwain. It goes from LighterAndFluffier to DarkerAndEdgier in a serious MoodWhiplash, thanks to the author's personal issues at the time.

** The Gray's Sports Almanac in ''Film/BackToTheFuturePartII'' allowed Biff Tannen to become wealthy by placing bets on the outcomes of sporting events when his future self gave it to him in 1955. What makes it work is that the Ripple Effect ensures that the Almanac will recursively update to reflect the changes in outcomes as a result of his prior betting, meaning it'll always be accurate. He then uses the money to become a CorruptCorporateExecutive and ruin the lives of Marty (and everyone else in Hill Valley), forcing Marty and Doc to go back in time and stop it.

* In ''Literature/ArtemisFowl: The Eternity Code'' Artemis steals some fairy technology (which is at least 20 years ahead of human tech), builds a computer out of it, and offers to sell it to a ruthless multi-billionaire. Said billionaire then steals the computer and shoots Butler. [[spoiler: He gets better.]]

* In ''Series/StarTrekEnterprise'', when [[spoiler:stranded]] in the 29th century, Archer finds a book about [[BigBad the Romulan Star Empire]]. Luckily, Daniels is there to stop him from reading it. When they finally encounter the Romulans in a later episode (but do not see them), Archer mentions the book title.

** One of the comics actually referenced that event when various representatives were at Admiral Kirk's trial including one from that planet, with the only result being that the representative simply gives it back to [=McCoy=] after saying how he'd left it behind. (They had still kept their original gangster society, though the profits had been invested in things like schools, libraries, and hospitals. What Kirk hadn't anticipated was that as the new boss, they had saved 10% of the take as Kirk's personal cut.)
** The ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'' writers at one point considered doing an episode that revisits the planet and finds that all the inhabitants are now dressing up as Kirk and Spock. This episode was to be a Star Trek 30th anniversary celebration, and was dropped in favour of "Trials and Tribble-ations". Considering how good "Trials and Tribble-ations" turned out, they probably made the right choice. The concept was later picked up in a comic.
** The 1989 tie-in book ''[[http://memory-alpha.org/wiki/The_Worlds_of_the_Federation The Worlds of the Federation]]'' had the same idea. When contact was re-established sometime around the Next Generation time period, the entire planet had restructured their society around TOS-era Starfleet and extrapolated enough technology to build a working starbase and apply for Federation membership.

** There was also the Next Generation comic issue "A Piece of Reaction" which follows the same plot (more or less).

** In the first draft of ''Film/BackToTheFuture'', Marty revealed to 1955 Doc that all his crazy inventions could be cheaply powered with Coca-Cola (ItMakesSenseInContext... [[ItRunsOnNonsensoleum well, almost]]), so when he traveled back to 1985 he actually ended in an alternate reality where everything was a {{Zeerust}} '50s rendition of the future, with hovering cars and robots everywhere powered by Coca-Cola. The dystopic part? [[ALittleSomethingWeCallRockAndRoll No Rock and Roll!]]

* The ''Literature/SixteenThirtyTwo'' series is about a small town from West Virginia sent back to the central Germany during the UsefulNotes/ThirtyYearsWar, so almost every object in the town is a TimelineAlteringMacGuffin, particularly books telling of events beyond the point at which they arrived in seventeenth century Europe. [[spoiler: The protagonists eventually take advantage of this by ensuring that only inaccurate transcriptions of uptime books circulate outside their territory, causing the royal houses of Europe to make some drastic miscalculations such as attempting to settle the Florida Everglades looking for gold.]]

*** "Future's End" has a 29th Century timeship that was sent back to 1967, although this results in a StableTimeLoop, since the technology boom of the late 20th century turns out to be thanks to the reverse-engineered tech from the timeship. Interestingly, the 29th century technology helps create the "holo-emitter" the Doctor uses for the rest of the series, so the timeship was a TimelineAlteringMacGuffin to the 24th Century as well.

* In the ''Series/DoctorWho'' [[AudioPlay/BigFinishDoctorWho audio drama]] "Colditz", it's discovered that their accidental appearance at Colditz Castle goes horribly wrong, and Nazis from the 1960s reveal they got the ''TARDIS''. The twist is that [[spoiler: the TimelineAlteringMacGuffin isn't the TARDIS, but a CD Player which leads to the getting to the concept of LASER quicker than they were supposed to, thus having them win the rocket race, making the V missiles more deadly than they were and eventually letting the TARDIS end up in their hands.]]

* ''WesternAnimation/{{Gargoyles}}'': Xanatos' claim that he is a self-made man is apparently very, very true; when he and several others end up transported back to ancient Scotland (it's a confusing tale), Xanatos takes a moment to take a single coin of the time period, seal it in an envelope, and date it to be delivered to himself when he would be a young man in the future. He would then use said coin to invest and grow into what would become his future extremely powerful multinational company. Which would raise the gargoyles. Who would end up with [[TimelineAlteringMacGuffin the Phoenix Gate]]. And he'd end up traveling back in time with them. [[StableTimeLoop To send himself a coin.]]

* The Creator/HarryHarrison novel ''A Rebel in Time'' subverts this. A racist colonel, Wesley McCulloch, goes back in time with Troy Harmon, a black officer, following him, assuming the man is going to give modern weapons to the Army of Virginia and thus help the South win the Civil War. He's confused when Perry instead plans to arm small groups to seize key Union towns. In their final confrontation, the colonel asks why Perry would do this when John Brown tried and failed. Perry's dying words: "Who's John Brown?" Going over his effects later, the colonel realizes that Perry (who barely passed high school and a horrible student of history) just happened to be basing [[CriticalResearchFailure his entire plan]] on the ''one'' book on the Civil War that ''didn't'' mention John Brown or the raid on Harper's Ferry.

* The Creator/HarryHarrison novel ''A Rebel in Time'' subverts this. A racist colonel goes back in time with a black officer following him, assuming the man is going to give modern weapons to the Army of Virginia and thus help the South win the Civil War. He's confused when Perry instead plans to arm small groups to seize key Union towns. In their final confrontation, the colonel asks why Perry would do this when John Brown tried and failed. Perry's dying words: "Who's John Brown?" Going over his effects later, the colonel realizes that Perry (who barely passed high school and a horrible student of history) just happened to be basing [[CriticalResearchFailure his entire plan]] on the ''one'' book on the Civil War that ''didn't'' mention John Brown or the raid on Harper's Ferry.

* ''Manga/MahouSenseiNegima'':

* In Pre-Crisis [[Comicbook/{{Superman}} Superman]] stories, it was well-established that changing the past was impossible. One issue of ''World's Finest,'' however, saw the time travelling villain Chronos acquire the means to "interactively" time travel, so he ''could'' change the past. Fortunately, he never gets the chance. Instead, [[Comicbook/{{Batman}} Batman]] gets sent back in time to the night his parents were murdered, tempting him to SetRightWhatOnceWentWrong at the expense of the future he knows. Fortunately, he resists the temptation, and Superman is able to bring him back to the present.

** In ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]'' the player gets to read one for the first time. If opened near a temporal rift known as the "Time Wound", the Scroll lets yousee an important piece of the past. If used anywhere else it, temporarily strikes you blind. The only reason why it only ''temporarily'' strikes them blind is because the Dragonborn's soul technically exists outside of time also. (Several more Elder Scrolls play into the plot of the ''Dawnguard'' DLC, though you'll only need to gather them there. A [[TheOrder Moth Priest]] will read them for you, and his blindness is ''permanent''.)