Time Travel is a pretty stock speculative fiction plot, but it has to be handled carefully in a series that isn't expressly about time travel. If the characters can simply jump back in time to prevent every catastrophe time traveling can quickly become a Plot Tumor.
One way to avoid this situation is to make time travel something that can't happen intentionally, or at least is very difficult to replicate or control. Instead of using a time machine, the characters stumble into a Negative Space Wedgie or their FTL drive malfunctions or an explosion tears open a hole in spacetime.
Alternatively, in a work where time traveling is possible, an accident may occur that causes unwanted time travel. It could be a malfunctioning Time Machine either randomly transporting people, or putting them in random times. Something unwanted may happen during the process of time traveling that the traveler ended up in a random time and/or place.
Contrast Casual Time Travel.
Anime and Manga
- In Dropkick on My Devil, one episode has Jashin accidentally activate a time travel spell while cooking curry. She ends up transported back to when she and her friends were kids who notice she looks like a bigger version of Jashin and want to know about the future.
- In Spider-Man 2099, Miguel O'Hara (the titular Spider-Man 2099) and Peter Parker wake up in each other's beds, as they got caught up by an identical scientific experiment conducted in both their eras.
- In Mass Effect: Murphy's Law, a machine below Area 51 known as the Spacial Distortion Device is responsible for sending the main character and his best friend to the future, though how it did this without killing them isn't immediately known. Not only was the jump to the future an accident caused by experiments with Element Zero, but it also ended with the destruction of the device itself, making the trip a one-way deal.
- In Ways To The Future (link), a Laverne & Shirley fanfiction, Laverne and Shirley are sent forward in time (from the sixties to the noughties) because Laverne pressed a button, not knowing what it did.
- In the Italian film Non ci resta che piangere (Nothing Left to Do But Cry), the story kicks off with Saverio (Roberto Benigni) and Mario (Massimo Troisi) stuck in a huge rainstorm. They see a light coming from a small inn and decide to spend the night there. To their astonishment, when they wake up the next morning, they have inexplicably traveled to Italy in the year 1492.
- In Spider-Man: Into the Spider-Verse, Kingpin's particle accelerator summons the other spider-folk to Miles Morales' universe (set in the modern day of the early 21st century), but their timelines don't always match. The alternate Gwen Stacy's calendar differs by a week, while Peni Parker is from the year 3145, and Spider-Man Noir grew up in New York just before the outbreak of World War II.
- Star Trek (2009): In 2387, Spock creates an artificial black hole in an attempt to limit the damage caused by the Hobus supernova, which has already destroyed Romulus. He is promptly attacked by the Romulan ship Narada, in revenge for his failure to save their homeworld. Both the Narada and Spock's ship, the Jellyfish, get pulled into the black hole, which turns out to have created a rift in space-time, depositing them in 2233 and 2258, respectively. Nero and his crew subsequently take the opportunity for some pre-emptive (and extremely misplaced) revenge against Starfleet and Spock himself.
- In Animorphs a "sario rip" is a tear in space-time produced by a massive discharge of energy. The first time it appears in the series it's produced by the intersection of a pair of starship-grade dracon beams, the second by a nuclear submarine Going Critical.
- Isaac Asimov's Pebble in the Sky: Joseph Schwartz is a fairly average man from our modern day (of the mid-twentieth century), when an accident at a local university with a crucible full of subcritical uranium creates a cone of destruction as it sends only things within the cone into the future. The lack of transition initially gives Schwartz the impression that he's an amnesiac and he's unable to speak the future language. After being experimented on, he begins to adjust to the strange future, learning that he's currently in the year 827, Galactic Era.
- Isaac Asimov and Janet Asimov's The Norby Chronicles:
- Norby's Other Secret: This story introduces Norby's Time Travel ability, but because he's so mixed-up he can't control his built-in abilities, the initial trips, such as the Roman Coliseum and the Ice Age, happen without his intent and they have to figure out how to control it so that they wind up back home in the right time, not just place.
- Norby and the Queen's Necklace: The protagonists are re-enacting a (fictional) account of Marie Antoinette and her Necklace. As the replica is tied around her neck, they are suddenly transported to Paris, France, on top of the jewelers who made the original. Albany is forced to Time Travel again, leaving Jeff and Fargo to face accusations of theft by themselves. As Norby tries to rescue them and return the real necklace, the replica continues to mess with his ability to maneuver in time, causing several wrong destinations.
- A Connecticut Yankee in King Arthur's Court: The titular Connecticut Yankee is sent into the medieval era after getting hit on the head and knocked out cold.
- Charlotte Sometimes zigzags between this and Casual Time Travel. When Charlotte goes to boarding school she finds herself sometimes waking up in the 1918 version of the school and being called by the name Clare. Gradually she realises she is swapping place on alternate days with the girl who had her bed at that time. The girls are somewhat able to manage the situation between the help of Clare's sister Emily and a exercise book they can write messages to each other in and hide within the bed. That is until the school is evacuated due to the flu epidemic on a day that has Charlotte in 1918, stranding her in the year. For many weeks Charlotte is stuck in the past despite her and Emily's attempts to get back to the school and the bed for the crucial night's sleep that will swap the girls back to their proper times.
- In the short story "The Magic Boots", a man buys some boots but doesn't realise they're magic and they take him back in time to "the good old days", which seems to be the middle ages.
- The Empirium Trilogy: Simon uses his marque magic to create a bridge between his home kingdom and one of its neighbors, hoping to hide the newborn princess from the resident Big Bad. The Queen's final act of magic ends up changing Simon's spell from jumping space to jumping time. This thrusts both him and the princess 1,000 years into the future.
- Liv in the Future: Liv ends up in the year 3000 after she pokes a portal in the sidewalk with a stick.
- Andromeda has an episode where Trance Gemini takes a few wrong turns in the Slipstream and the Andromeda Ascendant winds up 300 years in the past at a strategic battle during the fall of the Commonwealth. When the Nietzscheans show up with a much larger fleet than recorded, it turns out to be a Stable Time Loop where they blew up a nebula. And given Trance's later-revealed precognition, might not have been so accidental after all.
- In Bewitched, one episode has Clara try to send herself, Samantha, and Darrin to Plymouth, and she does... but in the middle ages.
- Doctor Who: Ace got caught up in a time storm while trying to make C4 in her bedroom, it sent her from 1980s England to Iceworld in the year 2,000,000. Eventually subverted when it turned out the time storm was created by Fenris.
- Sir Arthur Conan Doyle's The Lost World: One episode features Professor Challenger trying to exploit the unique properties of a cave to redirect energy, believing that by using his machinery to manipulate he can use it to teleport them back to London. Instead it sends them two hundred years forward in time to a world ravaged by nuclear and viral wars, to the point most survivors live as slaves toiling to mine the few remaining natural resources. He manages to reverse the process to get them back at the end, but accidentally causes the entire cave to continue traveling back in time without them.
- Stargate-verse: When a Stargate wormhole passes near a star, solar flares can cause the wormhole to curve back to its starting location in another time.
- Stargate SG-1: In "1969" a solar flare sends SG-1 back to the sixties, they learn about the flare that can send them back from a note General Hammond gave them before the mission, as his younger self met them shortly after they arrived.
- In Stargate Atlantis, Sheppard is sent millennia into the future by a solar flare, arriving in a ruined Atlantis. A hologram of an elderly McKay (who has dedicated his entire life to making this work) greets him with a plan to use another solar flare to get him home. While they set up, McKay tells the story of how everyone died after Sheppard disappeared, and provides some information to help avoid the disasters this time.
- Stargate Universe: In "Time" the Destiny crew find their own bones on an alien planet, along with a Kino that has footage of what happened. Eventually they gather that their past selves ran into a solar flare when they tried to gate back to the ship, and figure out what they need from the planet. Unfortunately by then all but Scott have died so he waits for the flare and tosses through a Kino with everything they've learned.
- Star Trek:
- Star Trek: The Original Series: "Tomorrow is Yesterday", the Enterprise winds up in 1969 after an accident with a "black star" that requires them to go full warp in reverse to escape its gravity. They eventually manage to return to the 23rd century by invoking a similar effect with Sol. The light-speed breakaway factor proves replicable and is used again multiple times, most notably in Star Trek IV: The Voyage Home. (The Expanded Universe would later retcon that you need either previous experience or the original Enterprise engines [preferably both], which is why it's never mentioned in later installments of the franchise.)
- Star Trek: Deep Space Nine:
- In "Past Tense", Sisko, Bashir and Dax end up being transported to San Francisco in 2024 due to a transporter malfunction. Sisko and Bashir end up accidentally causing the death of Gabriel Bell, who was instrumental in changing the dystopian society that the world had fallen into, so Sisko must then take Bell's place to make sure that history follows the right path.
- And then in "Little Green Men", Quark, Rom, and Nog take a ride in Quark's new spaceship and try to drop Nog off at Starfleet Academy. Unfortunately, the contraband that Quark loads into the shuttle combined with an engine malfunction causes an accidental time warp to Earth in 1947 and they (along with Odo, who stowed away to catch Quark in the act of smuggling) end up causing the Roswell Incident. There's even a Call-Back to "Past Tense" when Nog, who is studying Earth history, mentions that Gabriel Bell looks a lot like Captain Sisko.
- In the Star Trek: The Next Generation episode "Time's Arrow", Data accidentally gets sent back to the nineteenth century while investigating how his severed head ended up in a cavern underneath San Francisco that had been sealed for almost 500 years. Turns out it's a bit of a Stable Time Loop situation.
- Supernatural: The god Chronos has the ability to Time Travel, but not only does he have no control over where and when he'll end up unless he engages in human sacrifice, he also cannot control when his powers activate.
- Todd and the Book of Pure Evil: A late Season 2 episode has its plot kicked off when a handicapped kid uses the Book of Pure Evil to give himself the ability to walk again. However, for some reason the Book also gives him the ability to run so fast he time travels. He ends up dragging Todd along with him, depositing Todd in a Bad Future where Atticus has taken over the town. Later, Todd figures out to get the handicapped kid to run backwards in time to take him back to the present, though he briefly overshoots and ends up in the past, where he gets some Myth Arc-critical information.
- In The Twilight Zone (1959) episode "Back There" it just happens to a guy who was discussing time travel on the anniversary of Lincoln's assassination.
- In The Umbrella Academy (2019), this is the case for Number Five, who had very little control over his time travel (which is just an extension of his base power of teleportation). In a bid to prove to Reginald that he could do it, he accidentally travels into a post-apocalyptic Bad Future and spends decades stuck there trying to figure out how to get home before the Time Police recruits him.
- In Warhammer 40,000 this can happen quite easily due to the Wibbly Wobbly nature of time in the Warp. The best example is the Lost Waaagh! of Warboss Grizgutz. As the Lexicanum puts it: "Due to a strange accident of Warp-travel he returned in system earlier than he launched the Waaagh! itself. Grizlutz murdered his doppelgänger to have a spare of his favourite gun and a resulting confusion stopped the Waaagh! in its tracks."
- Star Fleet Battles
- Scenario 500.0 in Nexus magazine #1. The Federation starship Kongo blunders into a combination spatial distortion/time warp which sends it 5,000 light years away and 120 years into the past. It is attacked by 20 Gorn sub-light battleships and must survive long enough for the time warp to open again so they can go back to the future.
- Scenario SP0802.0 "Conquest's Gate". A Hydran X-ship enters an ion storm in the year 210 and is sent back in time to the year 114. It attacks a Klingon fleet and destroys it, preventing it from invading the Hydran nation.
- Scenario SN15.0 "A Warrior's Death", which appeared in Nexus magazine #12. In it, a Klingon X-ship travels back in time after a sun goes nova nearby. The ship approaches a nearby Klingon border station in order to provide the Klingon Empire with its advanced technology, but the Klingons of the past think it's a Federation trick and attack them.
- Visigoths vs. Mall Goths: The Visigoths did not intend to time travel to the future, and the Mall Goth who summoned them to the 90s by Ouija Board is described as "careless." This bad first impression set the stage for each faction to consider the other as their Sitcom Arch-Nemesis.
- "Time Slips" are a phenomenon a person supposedly experiences when they find themselves in a different era. How long a Time Slip varies, ranging from a few minutes to several days to maybe even longer.
- Chrono Trigger: The game's events begin when Marle's pendant begins to glow and she gets sucked into a time portal while testing out Lucca's teleportation device at the Millennial Fair.
- Happens to a degree in Timeshift. The Beta suit that the protagonist wears is one of two prototypes for a time travel capable suit of armor, and when the game happens, neither are finished. Initially a component in the suit becomes damaged, and spits the player out days if not weeks before their confrontation with the Big Bad is supposed to happen, and the second time is when the protagonist stops his plot to steal the suit in the present day, which causes the suit to teleport the protagonist to an unknown point in time to stop an imminent paradox from occurring. Not necessarily accidental time travel, but rather uncontrolled time travel.
- Steins;Gate has a variation in that it's a text message, not a person, that gets sent back in time by accident. The result is that the present gets shifted into a different timeline, and protagonist Okabe (the one who sent the message in the first place) is the only one who recognizes that anything's changed. It later transpires that the "gel-bananas" he's been cooking in his microwave are also being inadvertently sent back in time.
- This trope sets the entire plot of Live With Yourself into motion. At the very beginning of the series, protagonist Todd encounters a time machine and accidentally pulls three other Todds from varying points in time into the present.
- Ben 10: Alien Force: In the 50s, a time travel related science experiment went wrong, throwing the now-named Professor Paradox outside of time and giving him the eventual ability to time-travel at will.
- Captain Caveman and the Teen Angels: In "Prehistoric Panic", Captain Caveman carries the Teen Angels' van uphill so they can go skiing. He goes Too Fast to Stop, however, and they end up thousands of years in the past. Cavey is reunited with his parents, but they never ask about the tall, oddly dressed females who have hair only on the tops of their heads.
- Futurama: "Roswell that Ends Well", the Planet Express crew wind up causing the 1947 Roswell crash after Fry tries microwaving popcorn during a supernova.
- Johnny Test: In "Johnny Sonic", Susan and Mary give Johnny a scooter they created in the lab when they see how desperate he is for a faster scooter. The thing is, said scooter can go fast enough to travel to the future, something they don't tell his brother as part of a prank. However, they weren't aware the scooter would cause so much havok in the town, to do point where Johnny and Dukey are wanted by the police.
- Justice League: In "Hereafter", Toyman builds a machine that he assumed was a Disintegrator Ray and uses it to vaporize Superman. Said machine actually turns out to be a weaponized time travel machine that wound up sending Superman 30,000 years into the future. The Vandal Savage from that time period mocks Toyman for not understanding what he created and for underestimating its power.
- The Powerpuff Girls: In "Speed Demon", the girls fly so fast they accidentally end up fifty years in the future, where HIM has taken control and turned the planet, including Townsville, into a Crapsack World.
- The Secret World of Santa Claus: In "The Return of Santa Claus", Jordi builds a teleporter designed to move objects from one booth to the other. When Santa and the elves all cram themselves inside one booth while the machine activates, Gruzzlebeard sneaks in and cuts the cable connecting the teleporter booths, causing the protagonists to be accidentally hurled into a Bad Future where the village has been enslaved with Gruzzlebeard as its tyrannical dictator who has erased the existence of Christmas. The gang manage to get back to the present by repeating the same action and stop the events that cause this future to occur.
- The Simpsons: In the "Treehouse Of Horror V" episode segment, "Time and Punishment", Homer breaks the toaster after getting his hand stuck in it twice. When he tries to fix it, he accidentally creates a time machine that takes him back to prehistoric times when he tests it. Remembering the advice his father gave him on his wedding day, Homer tries not to disturb the past, but every time he kills a creature that bothers him, the future is changed in different ways.
- SpongeBob SquarePants: The plot of "Dunces and Dragons" was started by SpongeBob and Patrick being bucked off a seahorse and somehow being sent back to Bikini Bottom in the Middle Ages.