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A Sub-Trope of For Want of a Nail, when the changes between two versions of history seem unlikely (even by chaos theory), or even outright impossible, from the particular change in the past. Even if the timeline is set right, there might be some changes that just don't make sense, even by how things were set right.

The key is that you cannot see any direct explanation for the changes. If you knock down a tree in the past, and the park the tree was in is photographed later on, seeing the tree missing in the new timeline is not this trope. That's just continuity. It would have to be the bench being repainted, even though you didn't do anything to the bench.

This used to be played straight, but out of a need to avoid making the Timey-Wimey Ball even worse than it is, most serious time travel stories these days try to make the timeline changes credible. Thus it's usually Played for Laughs now.

Compare Butterfly of Doom. Contrast In Spite of a Nail.

Examples of Non Sequitur Causality include:

Comic Books

  • Many issues of Marvel's What If...? fall into this trap.


  • In Robert Silverberg's short story "Needle In A Timestack" time travel is common for holidays, so minor changes (your car was a grey Toyota, now it's a silver BMW) are just "the little annoyances of modern life". Unless your wife's ex-boyfriend is trying to undo your marriage.
  • The Power of Un uses this as well - the carnival is subtly different (paint colors and such) even though the timeline started changing just that morning.
  • In The Science of Discworld II the mages' meddling with time (trying to make sure Shakespeare is born and becomes the great poet he is supposed to be) accidentally results in the first potato being brought to Europe.
  • Dirk Gently's Holistic Detective Agency has a perfectly lampshaded use of the trope. Early in the book, it turns out that in bringing the coelacanth from prehistory to the early 20th century to be rediscovered, the dodo went extinct, and that was the end of a short chain of similar changes. At the end of the book, after the main characters go back to the dawn of life on earth, Dirk finds out that his secretary was still working for him, and a cat that he'd spent the last eleven years searching for had never gotten lost in the first place.
    • Another odd twist from this book: the close-enough timeline that Dirk and the other protagonists wind up in is almost certainly ours. Until they started messing about with time, Johann Sebastian Bach had never become famous, since the aliens' music hadn't been shown to him...
  • Dragonlance's The War of Souls trilogy.
  • In The Hitchhiker's Guide to the Galaxy using the Infinite Improbability Drive on the starship Heart of Gold tended to cause this throughout the universe. That being one reason why it was replaced with the Bistromathic drive.

Live-Action TV

  • Red Dwarf uses this in "Timeslides", when the last change to the timeline puts everything back how it was except that Rimmer is alive. He dies seconds later and the change in his backstory is apparently forgotten.
  • Stargate SG-1: After SG-1 is sent back in time they start a revolution against the Goa'uld, the problem is that the Goa'uld take away the stargate and the alternative SG-1 has to go back in time and put things as they were. When the timeline is corrected, the only difference is that Jack's lake now has fish.
  • Many small changes to the barracks and a few minor discrepancies in continuity in Lost have been theorized to be because the time-travelling survivors altered some minute details of the past when the island was shifting through time. These include Rousseau forgetting Jin and Aaron's birth being slightly different.
  • Season 4 of Eureka: Despite removing one of the town's founders from the timeline in 1947, the biggest changes that occur in the resulting future are that a few people have different jobs, Henry's married, and Jo's not dating Zane anymore.
    • And Allison's kid is no longer autistic.
      • And a statue has changed materials.
  • In Primeval, leaving a couple of Future Predators in the past somehow changes Claudia Brown into Jenny Lewis, gives the team a new HQ, and alters Connor's dress sense.
    • It also added a minor Big Bad named Leek.
    • Interestingly, killing an entire tribe of proto-hominids in the distant past did absolutely nothing.

Video Games

  • Winning the game in Dark Fall: The Journal undoes something unnatural that'd happened at the Station Hotel in the 1940s. In the sequel, Dark Fall: Lost Souls, the same hotel has suffered severe bomb damage from WWII, which hadn't been evident in the previous game. Unless writer Jonathan Boakes is implying that the unbound Dark entity had somehow deflected a bomb in the first game's timeline, and did so several years before this Ultimate Evil actually broke loose...

Web Comics

  • Misfile has an example that starts out being completely impenetrable though the connection is eventually revealed: When main character Ash wakes up one morning having been retroactively turned into a girl: not only is he now female, as far as most of the universe is concerned he always WAS, with resulting changes in his wardrobe, photo-albums, relationships... and, strangely enough, the car he'd stashed in his garage because he couldn't afford an engine for it suddenly has exactly the engine it needs. Eventually it's revealed that his estranged mother -- whom he'd lost touch with in original timeline but had already reconnected with as a girl -- had not only provided her with tons of clothes; she'd also bought her "daughter" a new engine for her racecar, perhaps to assuage the guilt she felt over abandoning her in childhood.
  • In one issue of PS238, Tyler is shown glimpses of alternate timelines in which he was born with different superpowers. In most, the visible changes make sense as consequences of that Tyler's powers, but there's one where everybody is in the middle of a crisis that starts up ten issues later in the main storyline, and there's no obvious reason why it should happen sooner in the other timeline just because Tyler has gravity-manipulating powers.
    • It's probably not happening earlier. The castle is 'outside of time', and therefore the mirrors can likely show whatever portion of the timeline they feel is significant.
      • Nobody actually says they can, though, so the default implication is that they're showing what Tyler would be doing right now in that other timeline.
      • Possibly a WMG, but since HE was the baseline human in the main timeline, the aliens may have targeted someone else, possibly earlier, leading to mass infection with their virus.

Web Original

Western Animation

  • Many of the timelines seen in The Simpsons episode "Treehouse of Horror V" (e.g. donut rain as a result of killing dinosaurs). The story ends with everything normal, except for people having long, forked, prehensile tongues.
  • In a Wonderful Life episode of The Fairly Odd Parents, it turns out that if Timmy had never been born, AJ would have hair, Elmer wouldn't have a boil and a non-braceface Chester would have Timmy's fairy godparents.
    • In another episode, Timmy went back to help his Dad win the trophy he accidentally melted. He comes back to find that the Internet is called Timmy and his name is Internet. Of course, he meets a younger Bill Gates who suggested it.
    • Possibly something of a Genius Bonus, since Tim Burners-Lee, (who invented the World Wide Web[1] by way of being in charge of the team who developed HTML protocols) originally planned on calling his invention The Infomation Mine, before realising the acronym was "un peu egoiste".
  • On Family Guy, Peter went back in time to relive his teenaged years and as a result Lois ends up married to Quagmire and Peter is married to Molly Ringwald. Also Al Gore is the President, we have universal health care, no crime or poverty, non-polluting flying cars that run on vegetable oil, and Dick Cheney, Antonin Scalia, Karl Rove and Tucker Carlson are all dead. But worst of all, Chevy Chase is hosting The Tonight Show. Peter manages to fix everything, but Roger the alien is now a member of the Griffin household.
  • Inverted in the Futurama episode "The Late Philip J. Fry," Professor Farnsworth assassinates Hitler in the early 1930's in one timeline and accidentally assassinates Eleanor Roosevelt in another but in both cases the year 3010 they return to appears to be exactly the same, except for being ten feet lower and five feet to the right.


  1. Not the internet, that's merely the result of computer networds growing large enough to cover the Earth. Burners-Lee himself credits the creation of the internet to Vint Cerf and Bob Khan who developed IP protocols.
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