Innocuously Important Episode
aka: Midnight On The Firing Line
An episode that seems to have no importance to the main Story Arc. After a major revelation later, the episode turned out to be much greater with significance in retrospect. May use a Chekhov's Gun and related tools, but telegraphing is avoided. Compare with Arc Welding where a Story Arc is created retrospectively from isolated episodes. Some examples of Jumping the Shark and Franchise Original Sin demonstrate the negative aspect of this trope (minus creators' intention) in which an episode or gimmick that at first appears silly but harmless turns out to be an indicator of future problems with the work. The examples, naturally, contain Major Spoilers.
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Anime and Manga
- Soukou no Strain: The fanservice episode redeems itself by setting up a major plot point that, later on, leads to many a Heroic BSOD, the outing of Sara's identity, the cementing of the True Companions, and the death of one unexpected major character.
- Madlax pulled this off with its Beach Episode, of all things, wherein Vanessa discovers that her employer is in cahoots with Enfant and eventually follows the clues all the way to Gazth-Sonika, unwittingly facilitating the meeting of the series' main protagonists, Margaret and Madlax.
- Fullmetal Alchemist loves doing this. The only even slightly minor character who has only one appearance was the terrorist from the fourth chapter. Even he shows up again. Both Bald (and Colonel Genz from the video game) appear in an advertisement for automail in chapter seventeen.
- In the 2003 anime version, you didn't think Russell and Fletcher would be content helping Bellsio with his farm for the rest of the show, did you? It seems Russell enjoys borrowing Ed's identity a bit too much. Too bad the second time he does it, the homunculi have Ed pegged as an enemy after the events of Lior. Also there's Rose.
- Tengen Toppa Gurren Lagann: Episode Five seemed like a fairly basic Released to Elsewhere plot made in order to add to the adventuring party, but the themes in that episode proceed to permeate the entire third quarter with glorious darkness.
- Gun Grave: The first episode of the anime might seem like just another mindless shoot-'em-up, but in the second episode you suddenly get to the real story, which is a mob drama.
- Cowboy Bebop has the episode Sympathy for the Devil. The first time through the episode might seem to be just another episodic romp, abet one with an immortal creepy kid. However, the episode not only hints at Spike's cyborg eye, but it also has a lot of parallels with the finale, from a villain who Spike's Not So Different from to Faye wishing Spike off as he's about to go on a presumably fatal mission, to Spike ending the episode pointing his finger like a gun and saying "Bang".
- The heartbreaking episode Affection in Ghost in the Shell: Stand Alone Complex is seemingly an episode made to highlight some of The Major's tragic backstory. Turns out it also tells Kuze's backstory too, and explains how he and The Major met when they were much younger. This does not become explicitly apparent until the final episode of the series, and doesn't become apparent to Motoko herself until right before the final scene of that episode.
- Steins;Gate: The first episode introduces the characters and setting, and begins to get into the concepts of time-travel used throughout the series, but the events of that episode also turn out to have far more significance than they'd seem. Okarin's time-travelling efforts in the final episodes show the events of that day as they truly unfolded, and towards the end of the last episode Okarin watches his past self discover Kurisu seemingly dead, remarking that he was to begin the most important 3 weeks of his life.
- While One Piece author Eiichiro Oda is a past master of the Chekhov's Gun, one instance that hits this trope is the Skypeia arc. A largely standalone arc with no immediate connection to the primary story except for the near-end reveal that Gold Roger had been there himself. Three very important things derive from this arc, however:
- The treasure obtained in this arc is used to purchase the materials for the Straw Hats' new ship, the Thousand Sunny.
- During Skypeia we see several characters with a Combat Clairvoyance power called "Mantra." Five arcs later, at Amazon Lily, we get implications that Mantra is, in fact, the first overt in-story use of a power known as Haki. Some time after that it's outright confirmed that Mantra is the name by which Skypeians know the "Color of Observation" form of Haki. After a Time Skip, several of the Straw Hats learn to use it.
- Skypeia introduces and is the source of Dials, a Bamboo Technology that main character Usopp then adopts and uses extensively until Usopp acquires Pop Greens seeds, as well as spawning a technological revolution that provides easier oceanic transportation and even a music industry that another main character Brook becomes a part of.
- The battle between Ace and Blackbeard at the tail end of the Enies Lobby Arc. The events and repercussions of the battle set up the single biggest conflict of the first half of the series later on.
- The episode during the Albasta Saga when Ace parts ways with the Straw Hats, giving Luffy a piece of paper. For a good long while, it appears to be nothing more than an ordinary piece of paper, until at the end of the Thriller Bark Arc, Lola gives one to Nami, explains that this is a special type of paper called a Vivre Card, and Luffy realizes it's just like his. He later sees that the card is beginning to burn and shrink, indicating Ace's life force is waning. But since Ace doesn't like people to fight his battles for him, and the burning down can reverse if the person is stronger, Luffy writes it off. Which is a HUGE mistake in the long run when he learns Ace has been sold out by Blackbeard and sent to Impel Down.
- Ace also mentions seeking out Blackbeard, a traitor to Whitebeard's crew who killed one of his crewmates. Drum Island Arc makes a passing mention to him and four other crewmates going on a rampage there, causing Wapol to lose his kingdom. In the Jaya Arc, there are several unusual people in Mock Town who could be confused for the local colors and general riff-raff. Then Luffy meets a complete stranger who shares similar ideals to his, and outwardly seems like a pretty likable guy, becoming a friendly aquaintance of Luffy's. Until he suddenly decks Sarkies of the Bellamy Pirates without breaking a sweat and tries (unsuccessfully) to claim Straw Hat's bounty for himself. Turns out he's Blackbeard, and is a backstabbing two-faced fiend, and those people from Mock Town are part of his crew, while another is off lobbying to get him a seat among the Seven Warlords. Nobody outside of Whitebeard's crew knows who he is since he's a relative upstart among pirates, but after Ace tracks him down and they finally fight, following the aftermath of the battle, everyone knows who Blackbeard is. By Impel Down/Marineford Arc, Luffy learns the truth about him, and it packs a wallop.
- In the Haruhi Suzumiya light novels, Endless Eight was exactly this. This short story gave the motivation for the whole fourth book, which most people didn't pick up on. So Kyoto Animation went all out and made EIGHT episodes out of it, setting up the Disappearance movie.
- In Naruto, the 'Kakashi Gaiden' arc was, for the longest time, just considered to be some interesting Filler that covered some of the backstory of Kakashi and explained where he got his Sharingan eye and somewhat "eccentric" mannerisms, put in between the pre- and post-timeskip stories as a sort of Breather Episode. With The Reveal that Tobi is really Uchiha Obito, who we saw die in that arc it becomes apparent that it was actually the introduction and backstory for one of the series' two joint-Big Bads!
- Chapters 9 and 10 of the Yu-Gi-Oh! manga, where Yugi duels Kaiba for the first time. What at first appears to be a simple Monster of the Week plot leads, directly or indirectly, to every following story arc that doesn't involve Dark Bakura as the main antagonist or the Magic & Wizards card game as the main game.
- After Caldina does a Heel-Face Turn in Magic Knight Rayearth, she tells Fuu that at least the Magic Knights have a goal- as compared to Zagato, whose reason for this hullabaloo is unknown. Until then, the three girls had genuinely thought that Zagato was simply out to take over Cephiro. Nothing else is mentioned about this for now- and the Magic Knights continue their mission. This is one of the first hints that there will be a Wham Episode coming up.
- Episode seven of Tokyo Magnitude 8 seems like a perfectly positive enough filler episode depicting how Mirai has grown and the beginning of a Sick Arc for Yuuki. That is until the last moment when Yuuki collapses. In the next episode he is brought to a hospital but subcumbs to his cranial injuries.
- In Transmetropolitan, Spider Jerusalem goes looking at the Reservations! Warren Ellis gets to write social science fiction! Too bad Spider gets exposed to the substance that leads to his debilitating brain condition...
- The 9th issue of Grant Morrison's run on Action Comics, sandwiched between "Superman Versus Brainiac, Fuck Yeah" and "Superman Versus Captain Comet (While Batman Chuckles At His Secret Identity Problems)" was an interlude involving parallel universes, a Corrupt Corporate Executive who creates a machine of incredible power allowing a monster to enter his world, and a black version of Superman who is the president of his America. The monster, Superdoom, comes to fight the main universe Superman in issues 17 and 18. It also turns out that the machine's creation is the result of events in The Multiversity.
- The Spider-Man arc "I Killed Tomorrow" is a fast-paced, fun beat-the-clock arc rife with humour and energy. The two-issue arc deals with Grady Scraps' invention of a Time Door that allows for travel to and from the future, and neatly wraps itself up at the end. It plays like a "breather arc" in the period between the intensity of Spider-Island and the epic sprawl of Ends Of The Earth. Flash forward to the Superior Spider-Man arc "Necessary Evil", and it turns out this Time Door is the passage through which Miguel O'Hara, Spider-Man 2099, comes to the present day and is subsequently stranded here.
- Grant Morrison's Seven Soldiers of Victory series consists of seven miniseries that all initially seem to be telling different stories, but ultimately overlap. Also, the Leviathan, a monster made up of hundreds of feral kids that appears in one issue of the Klarion mini-series, later turns up in Batman Incoporated as a sinister organization.
- The "Riddles in the Dark" chapter of The Hobbit is revealed to have been surprisingly significant when the reader starts with The Lord of the Rings.
- Harry Potter and the Chamber of Secrets is slow paced but sets up Harry Potter and the Half-Blood Prince. It set up the concepts of horcruxes through the diary, as well as cemented the connection between Voldemort and Slytherin. The basilisk fang from the Chamber was later used to destroy the horcrux, and parseltongue was useful several times in the series. And in one scene Nearly Headless Nick convinces Peeves to destroy a cabinet to distract Filch for Harry- said broken cabinet becomes a major plot point in Half-Blood Prince. Also, the book set up the Harry/Ginny romance. Even the romantic plot of Chamber of Secrets is revisited in Half-Blood Prince, but with the roles of Harry and Ginny reversed.
- Bridge of Birds: Every seeming Wacky Wayside Tribe turns out to be this by the end.
- In the Dirk Gently series, Dirk's "holistic" philosophy isn't wrong in the context of the books — even the aside jokes are relevant later on.
- The Hitchhiker's Guide to the Galaxy sets up a few of them, mostly in the first book. A person is mentioned in the prologue and then dismissed with "but this is not her story"; the same prologue is used in the fourth book, only now it is her story (as well as Arthur's). Then there's Arthur's first encounter with Vogons, in which he says that he wished he had a daughter so he could forbid her to marry one. Four books later, he does have a daughter, and she's quite rebellious—though she and the sympathetic Vogon character introduced in the sixth book never actually meet. Finally, there's that bit about the bowl of petunias thinking "Oh no, not again", and the book says that if we knew why it was thinking that, we might know a lot more about the universe than we do now. We find out the answer in the third book. Notably, Douglas Adams was making it up as he went along, and would deliberately leave threads like these dangling with no idea of what, if anything, he was going to do with them. So when he did tie up a loose end, it was as much a surprise to him as to the rest of us. Another example is the implication from Arthur's encounter with Agrajag in Life, The Universe and Everything that Arthur cannot die until he's been to Stavromula Beta, which doesn't even seem to occur to Adams until two books later, when he has to construct a kind of Shaggy Dog Story (and an incredibly lame pun) to wrap up a loose end he hadn't even acknowledged previously.
- Grave Peril, the third book in The Dresden Files series, has serious implications reaching all the way out until Changes. (And likely beyond, as books continue to be released. Word of God says that all the guests at that little party will be seen again.)
- Going back to the first book, Storm Front, the ritual used by Victor Sells is the same one the Red Court wants to aim at Harry in Changes, the 12th book.
- The prologue to A Game of Thrones is like this to the entire A Song of Ice and Fire series. The prologue to A Feast for Crows serves the same function within that book, setting up plot that doesn't truly get put into motion until the last chapter, some 900 pages later.
- The Warrior Cats novel Dark River is one of these. At first it seems to be an interesting romp based on forbidden love, but looking back on it with Omen of the Stars completed and Dawn of the Clans coming soon it's one of the most important books in the series. It introduces the Ancients (the shared root of the Tribe and the Clans), Rock (who is revealed in The Last Hope as the cat who gave StarClan the prophecies), Dark Forest cats entering the real world, and the Tunnels (a massive Chekhov's Location).
Live Action TV
- Babylon 5. Several episodes of the first season.
- The thirteenth episode "Signs and Portents". The episode's "A" plot is some fairly standard and unimportant thing involving Raiders [space pirates] and a Centauri artifact called The Eye. The "B" plot, involving the first appearance of the enigmatic Mr Morden and the question "What do you want?", turns out to be incredibly important and crucial to the rest of the series — but the episode's retrospective importance only kicks in at the first season finale.
Its importance was lampshaded by the fact that the entire first season was also named "Signs and Portents" (though a casual viewer wouldn't know this - the season titles only appeared on fan sites.) "Portents", of course, are hints about future events.
- The A Plot does have one rather important thing happen in it; it's the first appearance of The Shadows.
- "Midnight on the Firing Line" is the former Trope Namer. The first episode after the pilot movie, it featured subplots and character moments that the show kept referring to throughout many of its best moments over the rest of its run.
- "Infection", the fourth episode of the show, managed to introduce several elements that would become very important later on, including Interplanetary Expeditions, ISN, Earth's desire for advanced biotechnology and the first mention of previous Shadow War a thousand years ago - and certain revelations about Sinclair's past and how it drives his behaviour in the present. Not bad for what is almost universally considered to be a lackluster Monster of the Week episode.
- The thirteenth episode "Signs and Portents". The episode's "A" plot is some fairly standard and unimportant thing involving Raiders [space pirates] and a Centauri artifact called The Eye. The "B" plot, involving the first appearance of the enigmatic Mr Morden and the question "What do you want?", turns out to be incredibly important and crucial to the rest of the series — but the episode's retrospective importance only kicks in at the first season finale.
- Community foreshadowed Chang's rise to power at Greendale in several earlier season 3 episodes, including "Contemporary Impressionists".
- Doctor Who:
- "The Daleks" was initially written as a space adventure story based on 1950s sci-fi serials, with anti-war themes and some quirky Nazi-like "bug-eyed monsters" as villains. Due to the extreme popularity of aforementioned villains it is now impossible to watch the story without being aware that this is the Doctor's first encounter with the Daleks.
- "The Tenth Planet" has three main points about it that get very important later. It introduced the "Base under Siege" formula that would dominate Troughton's tenure and influence the show's slide from a Genre Roulette format into Monster of the Week, introduced the Cybermen (though they were given a soft-reboot a few episodes later), and ended with a shock twist of the Doctor suddenly turning into a totally different actor. All of these at the time were just decisions being made for that particular episode and Real Life Writes the Plot, but due to Who's Kudzu Plot nature all became very significant (although some in terms of the show's feel rather than in plot points).
- "The Web of Fear". Intended at the time as a sequel to an earlier story about the Doctor teaming up with the military and a now-older ally to fight killer robot Yeti in the London Underground. The impact is massive - here is where the Brigadier gets introduced (in fact, he's the prime suspect for being the Great Intelligence's vessel for most of the episode, something that would not have been done had they known he would be a regular), here is the start of the UNIT arc and here is the start of the "Yeti on the loo in Tooting Bec"-style horror that would form the Pertwee era of the show.
- The first episode of Season 6, Episode 1 of "The Dominators", introduces us to Cully, an ageing Man Child from an alien species with two hearts, whose disgruntlement with his people makes him crave adventure and go travelling in his ship with a bunch of awkward teenagers. He lands and his entire crew gets murdered. This is an innocuous opening for a filler story at the time, but takes on a new meaning when you compare it to the last episode of Season 6, Episode 10 of "The War Games", in which the Doctor is confirmed to be a Time Lord on the run from his boring civilisation and his crew get sent back to where they were from by the other Time Lords (including the implicit death of Jamie).
- "The Brain of Morbius" was intended as a Filler Bottle Episode, but several of the Doctor's throwaway lines in the story imply that the Time Lords aren't as godlike and advanced as they had previously been portrayed. This could easily be brushed off by the fact that the Doctor hates the Time Lords and (in that incarnation at least) has an unreliable grasp on reality, but Robert Holmes picked up on it and used it as Foreshadowing for his Wham Episode, "The Deadly Assassin", which revealed the Time Lords were a bunch of stagnant old politicians with Chronic Backstabbing Disorder.
- "Silver Nemesis" had Cybermen vs Neo-Nazis, but it set up the "Wolves of Fenric" arc with Ace and the Doctor as Chess Master motif which concluded in rather sinister style in "The Curse of Fenric".
- The ending of "The Shakespeare Code" includes William Shakespeare using words to stop the villains. The last episode in the season, "Last of the Time Lords", took that concept and turned it Up to Eleven. The relationship between the tenth Doctor and Elizabeth I is later explored in the 50th anniversary special.
- "The Long Game" sets up a lot of later events — including the Ninth Doctor's regeneration — as the Doctor's actions lead to "Bad Wolf". Meaning of course that it also has perhaps the most relevant title of the entire show.
- "The Unquiet Dead", which introduces the Rift in Cardiff. Without that rift, the events in "Boom Town", the show's first, third and fourth series' finales and "The End of Time" would not have taken place... nor any of Torchwood.
- "The Lodger" seems like a filler episode (albeit a fun one), but we later learn that the black TARDIS belongs to the Silence, the Big Bad of the next season. Craig returns that series for a single episode, where it turns out he's the source of the TARDIS-blue envelopes from the beginning of the season.
- In series 3 of New Who, the episode "The Lazarus Experiment" set up both Martha's family's betrayal to Harold Saxon/The Master, and the aging device was used against the Doctor in the season finale.
- Similarly, "Human Nature" and "The Family of Blood" appeared to be an updated telling of a Doctor Who novel, leading to a unique circumstance where fans familiar with the spinoff media were actually less likely to realize these episodes were this trope, which comes off as exceptional filler otherwise. In fact, they set up the Master's return.
- Lost had a lot of these.
- Sometimes the writers themselves didn't realize how important an episode would be until later, as was the case with Season 2's "One of Them", which introduced Henry Gale a.k.a Ben Linus, originally intended as a recurring character who would die after a few episodes, but who went on to become the Big Bad for the next season and a half, and who remained crucial to the show's mythology even after completing a Heel-Face Turn later on.
- Season 1's "House of the Rising Sun" appeared to be a standalone episode mostly intended to fill in the back story of Jin and Sun at first. Its B-plot included the discovery of two skeletons that weren't even mentioned after that point until season 6, but which turned out to be major figures in the island's history.
- How I Met Your Mother:
- At first glance the "Showdown" episode seems like pure filler with Marshall and Lily preparing for their wedding and Barney going on The Price is Right. However, we learn two episodes later that Ted and Robin broke up at this time. It also sets up Barney's story arc of searching for his father that dominates most of season 6.
- One episode features a jokey subplot in which Marshall is unable to have sexual fantasies about women other than Lily without first imaging an intricate scenario in which Lily dies of an unspecified disease and gives him her blessing to move on once she is dead. The widely-reviled ending of the show featured something similar, with the Mother dying of an unknown illness and Ted's children enthusiastically giving him the blessing to go after Aunt Robin years after the fact. Given that this ending was filmed between the first and second seasons, it's highly likely that the Marshall-Lily plot was completely intentional foreshadowing.
- In Star Trek: Deep Space Nine:
- An early random Ferengi comedy episode "Rules of Acquisition" reveals that something called "the Dominion" is a major power in the Gamma Quadrant. The war against the Dominion is the Myth Arc of the show.
- Season 5's "Rapture" was a heavy Bajor episode, focusing on the planet's future and Sisko's role as Emissary. The main thrust of the plot is Sisko gaining visions of the future, which are slowly killing him. Before Bashir operates to remove this ability, one vision was of locusts hovering over Bajor before moving onto Cardassia. A later two-parter saw the Dominion enter the Alpha Quadrant and set up shop in its newest member, Cardassia. The same two-parter also revealed that Bashir had been replaced by a Changeling by this time, offering a new reasoning for "Bashir" wanting to operate on Sisko.
- Star Trek: The Next Generation:
- The episode "The Neutral Zone" has two plots: the A plot is a fish-out-of-water story about twentiety-century earth humans running amok on the Enterprise; occasionally we touch on how outposts along the Romulan Neutral Zone have been disappearing. This secondary plot is the first time in the franchise that the Borg's influence was hinted at, and similar disappearances would be discussed in their first appearance ("Q Who") and the landmark Borg two-parter "Best Of Both Worlds."
- "Journey's End": While its primary purpose is to resolve Wesley's story, the Federation colonist subplot lays the groundwork for the emergence of the Maquis over on Star Trek: Deep Space Nine — which in turn serves as the catalyst for Star Trek: Voyager and the defection of Ro Laren during TNG's penultimate episode.
- Stargate Atlantis: In the first season, they encounter a planet that had been developing a drug that would make them immune to the Wraith feeding on them, but also has a 50% chance of killing the person injected. It seems like a one-off story, until the middle of season 4 when their enemy, a Wraith-turned-human-turned-hybrid gets hold of the drug and begins to spread it across the galaxy. It plays an important role in several episodes from then to the end of the series.
- "A Bugs Life," has a story about Peacekeepers and a virus capable of possessing people, but the reprocussions of that episode would echo throughout the series and beyond.
- "Beware of Dog" had a fairly ridiculous main plot, with a B plot of Crichton going crazy and imagining Scorpius around every corner — but it's a brilliant setup of the entire plotline for the rest of the season, one that would continue throughout much of the series.
- The very first time Crichton hallucinated Scorpius was in "Crackers Don't Matter", a nutty, off-the-wall episode where everyone's going crazy and fighting over crackers.
- "A Human Reaction", a well done though not especially memorable episode - until it's revealed a few episodes later that the major plot point of the entire series was set up during its events.
- "Won't Get Fooled Again" seems like just another one of the series' frequent visits to Bizarroworld, but the ending reveals the existence of the neural chip in Crichton's head and its accompanying mental clone of Scorpius, both of which are crucial to the Myth Arc.
- "Eat Me" is just another Monster of the Week episode, and just another episode where Crichton gets split into duplicates (yes, it happened more than once). Then at the end it turns out that the duplication of Crichton was permanent. Cue most of the rest of the season being split between two groups of characters on separate ships, each with its own Crichton.
- Buffy the Vampire Slayer.
- Three major villains in Season Six were all introduced through previous, seemingly "filler", episodes.
- "I Was Made To Love You" (and earlier, "Ted") seemed a bit out of place at the time of airing (robots? really?) but set up the suspension of disbelief needed for the Buffy Bot to exist in that series, which allowed Dawn to stay in Sunnydale after the events of "The Gift".
- 'Killed By Death'. Buffy is sick and ends up in hospital - a place she hates since her favourite cousin died in hospital when they were children. While the Monster of the Week in the episode (which was also responsible for her cousin's death) is dealt with, Sunnydale General ends up playing a big role in Season Five - not only does Buffy's mother Joyce end up with a brain tumour and spends a few episodes there, but we're also, at the same time, introduced to the character Ben Wilkinson, a young medical intern who serves as a possible Love Interest to Buffy and who turns out to be the mortal, human shell of Glory, the Big Bad of Season Five - Glory's plans, in turn, result in Buffy's death in the Season Five finale.
- The Pushing Daisies episode "Circus Circus". No other episode sets up as many of the major arcs and themes in the second season: the corrosive effect of secrets; something new beginning as necessarily implying something else ending; stasis as the opposite of life/death/rebirth; the impossibility of simply picking up a relationship where it was left off; one's persona or public self versus one's True Self; a parent's inability to recognize his or her child.
- The Battlestar Galactica first-season episode "Tigh Me Up, Tigh Me Down" was thought to be a comedy filler episode (the only intentionally comic episode in the entire show) revolving around a series of misunderstandings between Ellen Tigh (who unexpectedly reappears in the fleet) and Commander Adama (who believes Ellen is a Cylon sleeper agent). The whole episode climaxes in an amusing scene where everyone humorously works out their differences, and the matter is resolved. Three seasons later, in "Sometimes A Great Notion", it turns out this episode set up the eventual arc and reveal that Ellen was the final Cylon.
- The Mad Men third season episode "My Old Kentucky Home." On its face, the Four Lines, All Waiting story serves as a series of character vignettes bound by the "work disguised as fun" theme. However, this episode introduces us characters that become prominent in later episodes (Connie Hilton, Henry Francis); and story arcs that carry through the next couple of seasons (Peggy's introduction to the counterculture, Joan realizing that marrying her doctor is not going to give her the life she thought she wanted, Betty looking for a way out of her marriage, among others).
- Merlin had two:
- In the first series "The Gates of Avalon" was a fairly basic Monster of the Week story, in which Arthur is targeted by two murderous Sidhe, but it also introduces the fact that Morgana is a seer which marks out her entire Character Arc from then on.
- The third series had "Queen of Hearts", which seemed a one-off filler which once more returned to status quo by the end of the episode, but it also introduced the character of "Dragoon", Merlin's old-man disguise which he puts to even greater effect in series four.
- Series 2 has "The Lady of The Lake" introduce Freya, Merlin's love interest who dies at the end of the episode, but becomes The Lady of The Lake and helps Merlin retrieve Excalibur in the series 3 finale.
- In the second season of GARO called Makai Senki, there is a flashback episode, in which the childhood of the main character Kouga is seen. The episode seems rather unimportant, until the final episode reveals Kouga knew the Big Bad as a child, who made Kouga promise to kill him if he ever turns evil
- Power Rangers Operation Overdrive's "One Fine Day" was a lighthearted episode featuring the Rangers on a camping trip which gets interrupted when their enemies erect a forcefield to search for part of the season's McGuffin. A alien-powered human chain used as an attempt to pass through the forcefield is a major clue that that the Red Ranger isn't human when it breaks, foreshadowing his Robotic Reveal character arc a few episodes later and his death-seeking Heroic Sacrifice in the finale.
- Power Rangers RPM's "Tenaya 7" not only properly introduces the titular cyborg villainess but also before she blows her cover, a throwaway line about a metal detector getting "false positives" gains new meaning when in the two-part finale Big Bad activates the sleeper drones among half of Corinth's populace including the officer who says said line.
- Mighty Morphin' Power Rangers season 3's "Master Vile and the Metallic Armor introduces the Zeo Crystal which not only serves to reverse the time shift in the Alien Rangers arc, but also its later attempted theft causes the Command Center's bombing and later serves as the basis of next season's powers.
- And than Zeo mentions its Big Bad's ties to an "alliance of evil" which is later prophised in the Millennium Message of Power Rangers Turbo, then abducts mentor Zordon and plays a big role the Zordon Era's Grand Finale Power Rangers in Space.
- Fringe's Bizarro Episode, "Brown Betty" (2x19) at first appears to be funny Breather Episode after some important revelations in the previous four episodes. Walter tells Olivia's niece Ella a drug-addled musical noir-style detective story using all the regular cast members... then gives the story an incredibly dark and bitter ending about how only one man can have a mechanical heart and one must die without it. The ending reflects Walter's guilt about stealing Peter and irrevocably damaging the alternate universe and how he feels the only good he's ever accomplished has come at the price of destroying children's lives (ie, the cortexiphan trials). It reflects the major theme of the next season, that only one universe can survive; one must be destroyed, leading to the Bad Future glimpsed in the Season 3 finale, "The Day We Died". However, Ella rejects Walter's unhappy ending and creates an ending where the heart can be shared, symbolizing Peter realizing after seeing the Bad Future there is another option: he can bridge the two universes, which will heal them both. Peter even does this with the aid of a grown-up version of Ella Dunham, bringing it full circle back to "Brown Betty".
- Supernatural has the early episode "Phantom Traveler" which appears to be a straight Monster of the Week episode with the brothers having to exorcise a demon who causes planes to chrash For the Evulz. Not only do we learn later in the season that the one who killed the boys' mother and sam's girlfriend is also a demon but demons become the major threat for the next few seasons with the rise in demonic possessions being a major plot point.
- In the Attitude Era, it was told that each of the four McMahon family members owned one quarter of the WWF. And then came 2001. Linda's loss of the WWF stock to Vince during her breakdown, combined Shane and Stephanie's selling of their stock to purchase WCW and ECW during the Invasion set up the Brand Extension and the return to the WWF of Vince McMahon's new business partner and co-owner: Ric Flair.
- Who would have imagined that news of a host of WrestleMania 27 would bring not horrors of Justin Bieber, but the return of the Rock after seven years and his year-long feud with John Cena at WrestleMania 28?
- CM Punk's pipebomb would not only elevate him into a true main-eventer but would also set up the debut of "douchebag yesman" Wrestling/Laurinaitisnote but the fact that he mentioned being a "Paul Heyman guy" would later come into play when Heyman (also aligned with Brock Lesnar) returned at Punk's side after beating up John Cena (not to mention, the term "Paul Heyman guy" actually came into use).
- The New World of Darkness core rulebook began with a story about mechanical angels serving the enigmatic God-Machine. While popular, this didn't seem important until ten years later, with the release of the second edition, the God-Machine Chronicle, and Demon: The Descent, both of which involve the God-Machine heavily.
- The Magic: The Gathering expansion Mirrodin had a villain named Memnarch, a golem driven mad by a weird, glistening oil. Memnarch was defeated, but the oil remained. It turned out to be Phyrexian oil, heralding the corruption of the plane of Mirrodin into New Phyrexia seven years later.
- In Dragon Age II, the whole first act is this. It sets up many plot points and characters that become important several years later. In fact, that's all the first act is, leading the more impatient players to conclude the game has no overarching plot at all.
- Dragon Age II as a whole becomes this trope in light of new revelations and developments in Dragon Age: Inquisition. DAII was sometimes criticized for focusing on plot threads that appeared tangential to the Myth Arc developed in Dragon Age: Origins and its expansions, but some of those threads ( the red lyrium, Flemeth's connection to the elves, the entire Legacy DLC), turn out not to be tangential after all.
- In the original Kingdom Hearts, the story of the Deep Jungle world has Sora reacting to a slideshow picture of a large castle with an odd familiarity even though he'd never left the islands before, and Tarzan telling Sora, in response to the question of where he can find Riku and Kairi, "Friends here; *&&X%.", which turns out to mean that his friends are in his heart. During the games climactic level at Hollow Bastion, Tarzan's words turn out to be Foreshadowing since it's revealed that Kairi IS REALLY inside Sora's heart and since she came from Hollow Bastion, that was also the reason why the castle seemed so familiar to Sora.
- A lot of seemingly comical or nonsensical things in Hatoful Boyfriend take on greater importance in the Bad Boys Love route. Especially Anghel's entire route: his deranged ramblings, once the fantasy-JRPG metaphors are unraveled, include nearly everybirdy's backstories and motives in shocking detail.
- In the first Mass Effect game, there's a side mission that involves going to the Moon and helping shut down a rogue AI. The third game reveals that this was an early form of EDI, the AI on the second Normandy, who was recovered by Cerberus and rebuilt.
- Golden Sun: Dark Dawn's tutorial dungeon, Tanglewood Forest, is built around the concept of using light and warmth to dispel darkness and the unnaturally-empowered creatures therein. Two-thirds of the game later, a supernatural Total Eclipse of the Plot happens, covering half of Angara with darkness that empowers monsters...
- In Rayman Origins, after beating a level, you give your Lums to the Magician, who gives you Electoons and Lum Medals. This doesn't seem too special until The Reveal, where you find The Magician behind the machinery of Moody Clouds, using the Lums to power it.
- In Pokémon Black and White , Team Plasma's attempt to steal the fossilized dragon from Nacerene Museum becomes this when you learn that they're searching for an ancient legendary dragon, and what they needed was something else in the museum namely, the unidentified pretty stone being used as a placeholder.
- Likewise, the encounter with Team Flare on Route 10 and Geosenge Town in Pokémon X and Y turns out to be this. Initially, they don't reveal much reason for being there other than to study the strange stones in the area. In Geosenge, you see a Team Flare grunt run off towards a dead end in town and never come back. Later you find out not only is Team Flare's secret headquarters located in Geosenge town, but it's also the location of the Ultimate Weapon. Team Flare seeks to reactivate it using the energy from the stones on Route 10, which turn out to be the graves of Pokémon killed in war.
- The first mission in the original Final Fantasy, where you have to rescue Cornelia's princess and defeat the evil knight Garland in a laughably easy battle so the King can build a bridge leading you to the town of Pravoka. Talking to the newly-rescued princess while in the throne room results in her thanking you and giving you a lute. At the end of the game, you learn that Garland has enacted a plan to create a time loop to escape his death and becoming the god Chaos. The lute is used to get into The Very Definitely Final Dungeon.
- Gunnerkrigg Court seems to be using this heavily, as several chapters, characters and plot points that seemed to have nothing to do with the overall Myth Arc at the time (particularly Aly's transformation in "A week for Kat") have taken on greater importance later, especially after the events of Chapter 20. Even the second chapter, which looks like filler, contained set-up for what is now confirmed to be an Aborted Arc.
- Homestuck's intermission at first seems to be a completely unrelated, silly tangent that has no bearing whatsoever on the plot. Of course, everything in Homestuck is plot-relevant, and said intermission turned out to have a big impact on the trolls' session, especially after the EOA5 flash when Spades Slick kills Snowman and destroys their universe. In fact, the Intermission includes the first mention of the comic's eventual Big Bad. For some, as much as the first three acts could be considered this, appearing to be nothing more than a bunch of pointless gags, but in actuality setting up a lot for later on such as the bunny John receives as a birthday present, which ends up becoming incredibly powerful, reaching the hands of a villain, and in doing so causes at least half of the terrible things that happen during the kids' and trolls' sessions.
- Transformers: Beast Wars
- An episode near the end of the first season entitled "Before the Storm," which sets up the first season finale and a huge chunk of the second and third season subplots as well.
- Similarly, the second-last episode of the first season of Transformers Animated, "Nature Calls", was an odd episode that involved "space barnacles", but it also set up for Megatron getting his body back in the season finale.
- Also in Animated, the episode "Headmaster" seemed to just be another disconnected episode with a new human supervillain, except that the Headmaster would up responsible for (one of) Starscream's current predicament(s), as well as the introduction of Dirt Boss and the resultant effect on the Constructicons.
- Star Wars: The Clone Wars has the fourth episode of the second season seem like padding but it became the first of the five-part arc about the second invasion of Geonosis with the most gigantic battle thus far and the introduction of zombies in the show.
- The Camp Lazlo episode "The Engagement" contains ends with a joke where, after Jane's engagement falls apart, rather then recognize Lumpus' affection she starts flirting with the Navy Turtle, hoping to be engaged to him. The final season sees Lumpus attending their wedding and subtly crashing it, beginning his relationship with Jane.
- The Ed, Edd n Eddy episode "Ed, Pass It On" (from 2002) is about Eddy lying that his elusive older brother is returning to the cul-de-sac in an attempt to gain respect. When he supposedly does arrive (it's actually Sarah and Jimmy in disguise), Eddy reacts with absolute fear. Seven years later, the Grand Finale Movie reveals that Eddy's Brother is actually a sadistic bully who tortures Eddy for fun and all the stuff Eddy's been saying about him all these years were all lies so he can get respect from the other kids.
- The Venture Bros. takes this to an art form. Seemingly trivial details and bits of dialogue have a nasty habit of becoming the fulcrums to entire episodes, up to several seasons later. Case in point: In the Season 2 episode "ˇViva los Muertos!" Dr. Venture educates his newly-animated Venturestein with a series of videos depicting a Central American sweatshop. Three seasons later, in the episode "Venture Libre", we learn that Venturestein became rebellious because he recognized one of the boys in the videos when he was sent to quell a revolution.
- Almost everything that happened across the Myth Arc of ReBoot can be traced back to the simple act of Bob loaning Mike The TV To Hexadecimal in "Painted Windows". Before that, the show was episodic.
- The Young Justice episode "Denial" initially looks like a straightforward Villain of the Week outing. Ultimately, though it turns out that not only was aforementioned villain actually a member of the Light, the Big Bad group of the whole series, but he was the first member of the Light to appear in person. Adding to that, the episode launched the ongoing Dr. Fate subplot that would turn up again several more times during the season, hinted towards Red Tornado's ties to the Justice Society, and laid the groundwork for the Kid Flash/Artemis relationship as well.
- "Nightmares And Daydreams" from Avatar: The Last Airbender is a Bizarro Episode, with a plot that mainly focuses on Aang becoming too sleep-deprived and hallucinating. The B plot focuses on Zuko and Mai Getting Crap Past the Radar (Zuko sends the servants away, and they both sink out of sight on the couch) while Zuko worries about a war meeting. Then we have one scene near the end, not even three minutes long, where Zuko finally has an epiphany that sticks. The next time we see him, he's preparing to leave and join Team Avatar.
Zuko: During the meeting, I was the perfect prince, the son my father wanted. But I wasn't me.
- In the Grand Finale, the audience finally sees what happened during the meeting: Zuko inadvertently inspired the plan to use Sozin's Comet to burn down the entire Earth Kingdom in order to break the spirit of its citizens once and for all
- The The Avengers: Earth's Mightiest Heroes episode "Alone Against AIM" seems rudimentary at first, boasting a simple storyline in which Iron Man and some of his companions prevent AIM from stealing important Stark Industries data and armor. It does, however, contain at least two ties to the season's main arc. First, Iron Man introduces a new suit of armor, which he will continue to use up through the series finale. Secondly, Captain America (actually a Skrull in disguise) reveals to the other heroes during the aftermath that he managed to keep the data out of AIM's hands, but the Skrulls later use this information to implant a crippling virus into Iron Man's suit.
- Justice League was almost purely episodic for its first two seasons, and has several episodes which are used as the basis for the story arcs in later seasons:
- "A Better World", in which an alternate universe version of the Justice League assassinates President Luthor and seizes control of the government, becomes the basis for the conflict in the first two seasons of Justice League Unlimited.
- Similarly, "Twilight (of the Gods)" seems like a one-off until the two-part series finale, when Luthor, in an attempt to revive Brainiac, brings back Darkseid with Brainiac enhancements.
- The second episode of Scooby-Doo! Mystery Incorporated has a trip to nearby Gatorsburg and a quick capture of some (fake) gator people, but the important part looked like a throwaway scene at first. A flickering sign spells The Dog Dies. A quick scare for Scooby? Nope. A command, or perhaps a piece of advice, and something close to being Arc Words. The quick references to gator mines and wells also seem a joke, but even in a world full of people in ghost costumes, that's clue pointing towards something unnatural.
- Codename: Kids Next Door started its beard-growing with what just seemed like another of its early, one-off episodic stints, namely the episode where a baby network executive convinces the KND to let him use their satellite network, which turned out to be a plot to use his age-changing ray on the whole planet. The kids defeat the baby, but in The Stinger his age-changing device ends up in the hands of the Delightful Children...
- X-Men: Evolution features an episode in Season Two where a previously-unseen mutant enacts some plot that completely stumps the heroes and leave them wondering what the hell THAT was all about. The end of the episode reveals he is attempting to free Apocalypse. This isn't revisited until Mesmero turns up again Season Three, becoming the major running plot for the second half of the season, and culminating in Apocalypse being the Big Bad of the final season.
- The events in Family Guy episode "The Cleveland-Loretta Quagmire" would haunt Cleveland for years to come, such as in "Love Blactually," and eventually led to the existence of The Cleveland Show.
- Season 2 episode of My Little Pony: Friendship Is Magic It's About Time was a typical slice-of-life episode whith Twilight having to learn not to worry so much about what might happen tomorrow after spending the week trying to prevent upcoming disasters. In that episode, Twilight had to bring Cerberus back to the Gates of Tartarus where he belongs. In the Season 4 finale, we learn that Tirek, one of the most dangerous creatures in Equestria, escaped from jail that time.
- Beware the Batman:
- "Attraction" is a break from the League of Assassins storyline before its resolution. However, it also introduces Batman's possible identity crisis and instability, which plays a huge role in the second half of the season.
- "Nexus" introduces Harvey Dent, an important character in the latter half of the series. More importantly, the events of this episode parallel the events of three-part season finale on a far larger scale.
- "Games" has a rather self-contained plot involving Humpty Dumpty. Later in the series, we learn that the traumatic events of that episode caused Mayor Grange to resign, kicking off the mayoral elections that play a major role in the season finale.
- Adventure Time:
- The episode "The Enchiridion!", Princess Bubblegum sends Finn and Jake to retrieve the titular book. This is not a big deal until season 4 reveals that the book can opens portals to other universes. The Lich stole it from the heroes who then travels to a dimension where he plans to wish for the extinction of all life.
- In the episode "His Hero", Finn and Jake meet their hero Billy and try to emulate his non-violent lifestyle. The episode itself is quiet forgetable but it has the first brief appearance of the Lich, who will be the Big Bad for the next seasons, along with the Gauntlet of the Hero and Billy himself has a key role in the finales of seasons 4 and 5 albeit a posthumous one.
- The episode "The Creeps" seems like a random episode about a fake murder mystery. Except for the appearance of Shoko (Finn's past life) as a ghost as revealed in "The Vault".
- Gravity Falls has some tremendous hints to its big mysteries hidden in episodes that otherwise aren't massively relevant to the plot. "Carpet Diem", a first season episode, had a brief shot of Stan discovering an old pair of glasses slightly different than his own that was one of the biggest clues to the second season's Mid-Season Twist with the Author's identity revealed to be Stan's brother.
- Steven Universe often has mundane sounding episodes which end up having major character or plot related impacts. For example:
- "Steven's Lion" in which Steven adopts a pink lion, until "Rose's Scabbard" it's learned that Lion knew Steven's mom Rose Quartz and has many of her possessions in his fur.
- "Laser Light Cannon" That had the Red Eye, a Monster of the Week that seemed it had no importance. In "Marble Madness" it was revealed to be a probe sent by Peridot.