In the first episode of Naruto, all the members of the Rookie Nine are seen lined up for the Henge Jutsu evaluation. Sakura and Sasuke are even shown going before Naruto. In the manga, Sakura and Sasuke aren't shown clearly until a few chapters later (you can see Sasuke in the background of one panel though), after Naruto becomes a Genin, and the rest aren't introduced until the Chunin Exam arc.
Some of the dialogue is changed, as Shikamaru and Ino replace the generic students who complain about Naruto's mischief causing them to be tested on Transformation, and Shikamaru wondering why Naruto is among the graduates when they are assigned to teams, when both had been done by generic students who presumably went on to fail their Genin exams. In Episode 3, a few of the teachers appear while observing Naruto and Sasuke in the classroom, including Kurenai, who is incredibly Off Model, has the red and white on her outfit reversed, and has a different voice actor for that episode.
In the manga, the Akatsuki member Hidan was only seen clearly when he makes his first appearance in person, but in the anime he makes an appearance that is clearly him as a hologram during the Gaara Rescure requesting to be the one to take care of Team Kakashi.
Also Kakuzu as well.
In a particularly weird version of this, a Whole Episode Flashback of Jiraiya's has appearance by various ninja who would become the Six Paths of Pain back when they were still alive and normal people. However, in the manga we only saw one of them this way (another one we saw in the present before the past in both versions), while the rest were introduced in the present tense and mentioned to all be people Jiraiya meet in life.
There've been a string of these in the One Piece anime; Akainu appeared in the background of a group shot just over a month after his present design was unveiled in the manga, Jimbei was shown among the Warlords quite a ways before his proper, physical introduction, and Shiryuu's shadow showed up in Impel Down long before his existence is even hinted at.
Nami appeared in the first few episodes working independently before her proper introduction during the Buggy arc.
Kaworu Nagisa, who only appears in episode 24 of the Neon Genesis Evangelion TV series, is seen in the first movie of the new Rebuild of Evangelion tetralogy. This may have something to do with him being an Ensemble Dark Horse, though. He also shows up quite a bit earlier in the manga adaptation, and in pretty much every Alternate Continuity. Notably, however, he's much more clearly a villain in the manga.
Every major character appears in the first episode of the 2006 version of Kanon, save for Amano Mishio. Yes, Makoto is there. For those who kept trying to spot the Makoto Sawatari we know, it's not her that we see in the pilot episode, but rather, her fox form, the fox that Nayuki approaches on the hill is what we see.
In the first episode of Eyeshield 21, as Sena wonders what club to join, you can see Monta in the background, presumably stumping for the baseball team. Another early episode features Suzuna Taki, who's trying to track down her brother Natsuhiko; she shows up again during the Death March arc, which is where she first appeared in the manga.
Inverted in Tokyo Mew Mew: Minto, Retasu, Bu-ling and Zakuro appear in the beginning of the manga before passing through the Debut Queue, but are removed from the beginning of the anime.
Many of the angels that Misaki faces later in Kidou Tenshi Angelic Layer appear on a videotape that Icchan is watching early in the anime.
In the anime Mermaid Melody Pichi Pichi Pitch, Caren appears several episodes before she becomes significant to a plot, winning a beauty contest that the main characters and villains entered.
Caren notably made a cameo during the beauty contest story in the manga as well, though she did not take part in it like in the anime.
In the manga adaptation of Tengen Toppa Gurren Lagann, Nia is shown right after Kamina, Yoko, Leeron, and Simon leave Ritoona Village. There's also some Early-Bird Ship Tease for Dayakka/Kiyoh and Rossiu/Kinon.
In Gurren-Hen, Guinble makes an appearance just after the destruction of the Doten-Kaizan. He looks (appropriately enough) younger than he did in the original series.
In Lagann-hen, the Anti-Spiral's face briefly appears on the moon's surface just as Nia accepted Simon's marriage proposal.
In Bleach, The opening used during the Bount Arc had a Couch Gag which would show a picture of a different character each episode. One of these showed Grimjow who wouldn't show up until the next story arc. Other characters shown this way include Ulquiorra and Shinji.
Chad appears briefly in the second episode, offering to help repair Ichigo's house after the fight against Fish Bone D in the first chapter. In the original manga, he does not appear until Chapter 7 (which is shown in anime episode 4).
Similarly, Ishida is shown in art class (sewing, of course) a good six episodes before most of the main characters are even aware of his existence, much less that he's a Quincy.
In an odd case despite adding this scene his cameo from the manga during the Don Kaionji introduction was removed completely.
While less noticeable than the other examples, in the anime, Kiyone and Sentarou (Ukitake's bickering third seats) first appear in Ukitake's debut when he hears about Aizen supposedly having been killed. In the manga, a faceless messenger tells him, and Kiyone and Sentarou don't arrive until he calls them out of hiding a few chapters later.
Directly after Grand Fisher's loss to Ichigo in the early episodes, he's held down and had his mask ripped off by at least two other Hollows. Two of these were Aisslinger and Di Roy, the latter shows up much later as Grimmjow's weakest Fraccion and the former shows up at the beginning of the Hueco Mundo arc, guarding the underground area of Las Noches.
An early version of Shinji Hirako can seen in the first chapter's cover art page in the manga. He wouldn't make his official appearance in the series for another 182 chapters.
In the anime of Katekyo Hitman Reborn!, Tsuna passes by Ryohei, Yamamoto, and Hibari when he is running to catch up with Kyoko.
The anime's first episode of Detective Conan gives Conan's future first-grade friends speaking roles.
An episode of Urusei Yatsura featured a story in Feudal Japan with the cast playing different characters. Before the story itself begins, the cast breaks the fourth wall to explain what is happening... when all of a sudden Mendou shows up for the first time. When the others ask who he is, he calmly replies "My name is Shutaro Mendou and I will soon become a regular character on this show". He of course, joins the rest of the cast in the story. Sure enough, Mendou's "actual" introduction occurs a few episodes later without any mention of this. If you're going to do a Genji story, someone has to be To No Chujo (Genji's friend/rival), that's Mendo to a "T", continuity be damned.
The anime of Yawara! A Fashionable Judo Girl added a date scene with Yawara in the park with Kazamatsuri (who's trying to avoid all the girls he stood up) in episode #6. One of them (the one in the boat) is Yoko Nanda, who won't join the main cast until MUCH later (like, after the part that's come to the USA). Nanda's defining characteristic WAS her bad luck with men, so it works rather well.
In the anime, Maes Hughes first appears during the train hijacking incident and helps Ed and Al retake the train, despite not appearing until Chapter 6 of the manga. The first Brotherhood episode features an entirely new story that features cameos by some of the military characters.
In Brotherhood, Izumi and her husband make a brief background appearance behind a scene where Winry is at a train station. Even earlier, when Ed is giving a shortened version of their adventures in a flashback, she appears in silhouette when he talks about them getting a teacher. The same scene contains Mei Chang.
Also in Brotherhood, this is inverted with Yoki. His first appearance is reduced to a brief mention, and it gets properly told (uh...somewhat) in episode 39. The first anime had covered Yoki's story well, so it only receives a brief nod in the second to make sure that the climax gets its full time to shine. Yoki's story isn't the only arc covered in the first anime to receive this treatment.
Kimblee also appears in the first episode of Brotherhood; Isaac MacDougal offers to break him out of prison, but he refuses. He doesn't become important until much later.
Also in Brotherhood: Maria Ross can be seen briefly in episode 5 before making a proper appearance. Then, in episode 6, while Edward explains that alchemists usually encrypt their research notes, Berthold Hawkeye is shown.
Another inversion happens in Death Note, where L appears at the very end of the first chapter, but doesn't appear until the Interpol conference in the second episode of the anime. An early scene with Near, Mello and Roger (the man in charge of Wammy's Orphanage) is delayed, and they first appear when receiving word of L's death.
Also Matt appears in episode 32 in the anime with Mello
In the Fist of the North Star anime series, Kenshiro's girlfriend Yuria, as well as his nemesis Shin, appear as part of Kenshiro's recurring nightmares/hallucinations prior to their proper introduction in the story.
In the second anime series, the Governor Jakoh is the first character to appear in the anime, whereas in the manga version of the Tentei story arc, he doesn't show up until he is revealed to be The Man Behind the Man.
In the first live-action movie, Hanyuu appears behind Keiichi as a silhoulette just before he tears his throat out.
The Nurarihyon No Mago anime not only has Gyuuki, the first major villain, appear early, but practically has him appear every other minute for no real reason.
The end of the first volume of Hellsing Ultimate has a brief appearance by the Major, as well as a brief flash of him while Luke and Jan Valentine are discussing their role in the coming events. The actual manga has him make brief appearances just after the attack on Hellsing headquarters and during the meeting between Integra and Enrico Maxwell, before he is properly introduced to the story (both of these appearances are also in the OVA).
In Bakuman。, Kaya Miyoshi is briefly shown calling for Miho to come with her in the first episode of the anime. She doesn't appear until a few chapters into the series in the manga, when she meets the main characters on the roof. Koogy's music turns up a few times before he decides to make his debut as a mangaka.
In the manga adaption of Rusty's arrival in ThunderClan during Warrior Cats, Ravenpaw is in the camp. In the book, he didn't appear until later.
Moomin places Little My in storylines that took place before her debut in the original books.
In the Little Busters visual novel, Suginami-san and her Jerkass friends Katsuzawa and Takamiya don't show up until the beginning of Rin or Kurugaya's routes, but the anime briefly lingers over the three of them in an establishing shot of the classroom in the first episode.
In the Soul Eater manga, we first see Sid after he's zombified and fights Maka, Soul, Black Star, and Tsubaki. In the anime we see him an episode earlier, before he became a zombie, in a scene added to the anime where Soul and Black Star try to find out about Kid. Likewise, we see Harvar, Ox, Kilik, Pot of Fire, Pot of Thunder, and Hiro in the fourth episode of the anime instead of some unnamed background characters, as all of them were shown significantly later in the manga.
While it's only one episode early, In the Date A Live anime, when it suddenly starts raining during Tohka and Sido's first date you can see Yoshino in front of the arcade they take shelter in.
Keen-eyed viewers watching Attack on Titan will spot cameos added in the second episode. A young Annie appears among the refugees waiting in the bread line, while a young Reiner and Bertolt appear in the crowd during the announcement of the operation to reclaim Wall Maria.
When The Adventures of Tintin In The Congo was turned into colour, Thomson and Thompson were added into the scene where he is saying goodbye to everyone on the railway platform (they were not present in the original black and white edition). The pair made their first proper appearance in Cigars Of The Pharaoh.
Certain random background Legionaires were changed into Brainiac 5 when early Legion of Super-Heroes stories were reprinted, by simply recolouring them to Brainy's colours (purple clothes, green skin, blonde hair).
The graphic novel adaptation of the first Artemis Fowl novel features references to Opal Koboi and her company- both of which play major roles in the second book- that were not in the print version.
In the Mega Man comic, the Short Circuits in issue 4 had Proto Man, Rush, Bass, and Treble showing up, demanding their turn in the comic.
In the Noob comic, a minor character named Castörga appeared in the sixth comic. Its story happens during a period equivalent to that of early Season 3 of the original web/TV series, where Castörga has his first appearance in Season 3 finale.
In Project Tatterdemalion, a Bleach AU in which Hollows are the result of The Virus and shinigami those of its vaccine, a pre-Hollow Nel gets a brief cameo as a coworker of Ichigo's parents who was infected- well before the introduction of Arrancar, or indeed any version of the events of Bleach canon.
In Game Theory, several characters from later seasons, such as Zest, Quint, Megane, and Tiida take part the Jewel Seed incident. Teana also gets a brief cameo, and although the girl in a wheelchair is never actually named, it's pretty clear that she's Hayate.
Gil Graham is initially mentioned in passing and eventually appears himself along with the Liese twins. (In fact Lotte Liese is an Eleventh Hour Ranger.) Quint also holds a conversation with her husband Genya (another example of this trope) where they talk about the two girls they're trying to adopt - clearly Subaru and Ginga. And finally Lutecia appears as a baby.
Turnabout Storm'sfan novelization has a cameo from Flash Sentry in chapter 52. Keep in mind that Twilight doesn't even have her wings yet, so this is happening way before he is canonically introduced. The author has confirmed Flash is in the story as a nod to the movie. Shining Armour also counts, since he is introduced in the season 2 finale, and the story takes place before that point.
This can be seen in several super-hero movies wherein pre-transformed allies, sidekicks, or villains may make an appearance, whereas in the comics, their first appearance included said transformation. Billy Dee Williams as pre-Two-Face Harvey Dent in Tim Burton's Batman (though the former was replaced by Tommy Lee Jones by the time he actually became Two-Face).
The producers of The Dark Knight Saga originally wanted the DA in the first movie to be Dent, but decided they couldn't give him time to properly develop so they came up with another character instead. This, unfortunately, led the filmmakers to stridently avoid this trope.
Similarly, Samuel Sterns appears as a supporting character in The Incredible Hulk. His final scene appears to be the start of his mutation into The Leader.
In the two Iron Man movies, Captain America's shield can be seen on Tony Stark's worktable along with Thor's hammer. The Captain shows up in a block of ice for the alternate opening of The Incredible Hulk (2008) and got his own movie in 2011.
In the first film, Rhodey looks at the MK II armor, and says "Next time, baby!" He wears an upgraded version of that armor in the sequel.
Thor itself features a cameo by Hawkeye, who was featured in The Avengers, as well as The Cosmic Cube from Captain America: The First Avenger appearing in The Stinger. Also, the Infinity Gauntlet is visible in Odin's trophy room/weapon vault. Considering Thanos appeared at the end of the Avengers film, the possibility of the Gauntlet becoming more important later on could be a little more likely now.
The Special Edition's Mos Eisley intro has a cameo appearance of Dash Rendar's Outrider ship from Shadows of the Empire.
The planet Coruscant from the prequel trilogy is shown during the celebration sequence in the Special Edition of Return of the Jedi. The DVD version also adds buildings seen during the prequels.
In the film version of The Voyage of the Dawn Treader at the end we hear Aunt Alberta call up "Jill Pole's stopped by for a visit". Jill becomes an important character in the next story The Silver Chair.
Most adaptations of A Christmas Carol introduce Tiny Tim and often the rest of the Cratchits near the beginning of the story, while in the book they didn't appear until the Ghost of Christmas Present stave.
The Warcraft novels Tides of Darkness and Beyond the Dark Portal, novelizations of the Real Time StrategyWarcraft II and its expansion respectively, have this in spades, not only featuring characters from that time period that were only introduced in Warcraft III and beyond, but also updating the story itself in the light of retcons and heavy additions to the canon in later games. They're almost "the Second War as seen through the prism of World of Warcraft". Let's just say that the flashback in The Frozen Throne in which Gul'dan wanders into the Tomb of Sargeras is recited almost verbatim in the first book, and Auchindoun plays a much more extended role in the second, along with the introduction of the "new" draenei.
Those Doctor Who Novelisations that were published some years after the TV story was broadcast sometimes added in references to later stories. For instance, in the novelisation of Terror of the Autons, the bomb that the hypnotised Professor Philips uses to try to kill the Doctor and Jo was retconned into a Sontaran hand grenade. And there's the notorious line in the novelisation of The Time Meddler where the Doctor refers to the Monk as a Gallifreyan, leading fans who relied on the novelisations to believe that the Doctor's home planet had been named eight years earlier than it was on TV.
The novelisation of "Shada" contains a short scene where the Fourth Doctor and Romana gossip about the Corsair, a Time Lord created for the Eleventh Doctor episode "The Doctor's Wife".
In the Discworld novel Moving Pictures, the character Ponder Stibbons makes a few sparse cameos and all we really know about him is that he was the main characters's room mate, Ponder Stibbons then became a major character in any books featuring the wizards after that, and is considered one of the most intelligent characters in the series, the original main character of Moving Pictures however has never even been mentioned again.
I, Claudius did this in combining the novels I, Claudius and Claudius the God — a large part of the latter discusses Claudius' childhood friend and ally Herod Agrippa, despite the fact he is absent for much of the former, even though it is about this period of Claudius' life. For this reason, the television series introduces Herod as a character long before Claudius becomes emperor.
Babylon 5 did this with its TV movie In The Beginning. This prequel covers the apocalyptic events of the Earth-Minbari War ten years before the series. John Sheridan, the star of the series by this point, meets and interacts with many pivotal members of the cast. He goes on a peace mission with Dr. Franklin and G'Kar, and is interrogated by Delenn when the Minbari take them all prisoner. However, when Sheridan was introduced in Season 2, only Ivanova mentions having met him before— ironically, after the war was over and therefore not on camera for this movie. Bruce Boxleiter was the show's star, and it was unthinkable that a TV movie would place him in a supporting role. Showrunner JMS argued to fans that any reminiscences about the events in the movie must have happened off camera on the series.
True Blood has done this with a number of characters and concepts, most notably Sophie-Anne, the vampire queen of Louisiana, who has a cameo in season two of the series but isn't introduced until the sixth book. The last episode of season two also raises the question of "what" Sookie is, something that isn't asked, much less answered, until the later books.
Inverted in Game of Thrones, in which many characters (notably Edmund and Blackfish Tully) first appear later than in the A Song of Ice and Fire novels, to prevent the producers of the television show from having to cast someone for one scene in the current season and then hope and pray that they're still available for a much bigger part in a later season.
The Royal Shakespeare Company is fond of doing this to Launcelot Gobbo, the "fool" from The Merchant of Venice. The 1999-1994 run (with Christopher Luscombe in the role) combined the two "Prince of Morocco" scenes, so that Launcelot's first appearance came directly after the scene in which the bond is agreed to. He was depicted doing odd jobs around Shylock's office (preparing coffee and rearranging files) until the others exited, at which point he suddenly stepped out and gave his monologue—probably quite a surprise to audience members who thought he was just an extra! The current run gives him an even earlier cameo—the show's setting has been transposed to Las Vegas, and there's an Elvis impersonator walking around singing appropriate music. Guess who he turns out to be...
In the Ace Attorney case "Rise from the Ashes" (inserted at the end of the first game when it was updated from the Gameboy to the DS), Gumshoe gives Edgeworth a menu from a French restaurant that's just opened. You have to squint a little, since the picture is tiny, but the man on the menu is Jean Armstrong. Armstrong and his French restaurant don't show up until the third game.
Then again, in Japan, they've got the first four cases of the first game, and the two other games as the Gyakuten Saiban trilogy for the GBA. The fifth case was added in the DS remake, which came later, hence his apparition.
It introduced a Dub Induced Plothole in the french version, which tried to make Jean Armstrong sound less French, for obvious reasons. He was made Libanese in this cameo, but Italian in the third game, when translated there.
Yoshi made retroactive cameos in the Super Mario Bros.. trilogy by way of video game remakes. In Super Mario Bros. DX (a remake of the first Super Mario Bros..), there's a block hidden in each level in Challenge Mode, each holding a Yoshi egg. Collect it, and Yoshi will hatch out during the point tally. When Super Mario Bros. 2 was remade as Super Mario Advance, you can unlock an extra mode where you can find two Yoshi eggs in each level. Find all the eggs in each world, and Yoshis would hatch out of them. Finally, Super Mario Bros. 3 was remade for Super Mario All-Stars and as Super Mario Advance 4, and in both versions, the King of World 7 had been transformed into a Yoshi rather than a Piranha Plant.
A more straight example from that game would be the fact that the sprite used for the last example mentioned would later be used for the main sprite for Yoshi in Yoshi's Island.
Which actually previously appeared in the SNES version in Yoshi's Cookie, depending on your region.
The OVA prequel included with Mega Man X: Maverick Hunter X features a few cameos by characters who appeared in the later games of the series. Signas, who becomes commander of the Maverick Hunters, as well as Grizzly Slash and Commander Dragonfly, bosses from the fifth and sixth games respectively, are seen during a mission briefing as current hunters. Presumably one of the generic humanoid hunters is the Green Biker Dude, Memetic Badass Extraordinaire.
Cream the Rabbit can be seen as concept art in Sonic Mega Collection.
Miles "Tails" Prower is arguably this, if one considers Sonic CD to take place before Sonic 2.
In addition, Sonic himself made his first in-game appearance in Rad Mobile of all things, NOT Sonic 1. If the official release date can be uncovered, he may have even made his true debut in the obscure Sonic Eraser.
In the Anniversaryremaster of Halo: Combat Evolved, 343 Guilty Spark is introduced in a terminal message where he warns you that your ship is getting too close to the ring. The rest of the terminals delve into his backstory.
House of the Dead: OVERKILL's PS3/PC rerelease, Extended Cut, adds two extra chapters played as Action Girl Varla Gunns and her brother's Dumb Blonde girlfriend. In the second extra chapter, the player can catch a quick glimpse of the Crawler, the boss of the fourth regular chapter (not that this makes his appearance any less out-of-nowhere).
Vanilla Ice is seen playing card games with the D'Arby Brothers when Joseph is using Hermit Purple. He and Telence also appear in a photo of Dio created by Hermit Purple.
Giorno Giovanna is seen in background events with his dad, DIO.
Yoshikage Kira is the owner of the dog devoured by Yellow Temperance.
Illuso shows up Polnareff and Kakyoin talk about the non-existance of a world inside the mirror.
Josuke Higashikata, Yuriko Yamagishi, and Keicho Nijimura show up during Steel Dan's underclassman rant.
Rohan Kishibe is the mangaka who interacts with Boingo.
Page looks like Pesci, which doubles as a pun and then Straizo spares him, so he's alive during part 5 somehow.
In the Legion of Super Heroes cartoon, before he joined the Legion and coined his superhero name in The Substitutes, Matter-Eater Lad was a competitor in the Space Olympics episode "Champions." The other, rejected lame-power applicants also showed up in Lightning Storm for comic relief. Ultra Boy makes his first appearance as a competitor in Champions, as well.
Batman: The Animated Series established Harvey Dent as Gotham's DA and a friend of Bruce Wayne in two episodes before he has the accident that melts his face off.
The Spectacular Spider-Man: not only gives Eddie Brock an extensive role (influenced by his role in Ultimate Spider-Man), but also has Norman and Harry Osborn, The Sandman, The Rhino, The Shocker, Doctor Octopus, Curt Connors, and, possibly, Frederick Foswell, as supporting characters or minor villains before their inevitable darker turns, as well as, as said before, every named schoolmate Peter had in the comics, as well as (again, as noted above) Gwen Stacy, whose fate is well known. Felicia Hardy also cameos in costume in a Halloween Episode before her official introduction.
Cletus Kasady (Carnage's host) makes a cameo in the Christmas episode, had the series continued he probably would've become a recurring villain.
Morris Bench (Hydro-Man in the comics) and Roderick Kingsley (Hobgoblin in the comics) also made appearances, and Mac Gargin (Scorpion in the comics) was mentioned at one point. Had the series continued, all three villains would have likely been used.
Miles Warren also makes recurring appearances as an amoral and cold-hearted scientist who gradually takes over Curt Connors' lab, during which time he makes it clear he's interested in gene-splicing by transforming Kraven the Hunter. Had the series gone on he would have become the supervillain The Jackal (who splices his DNA with a jackal late in the comics) and probably done their version of The Clone Saga. They also point out that he is the brother of Peter's high school science teacher.
Also, a girl seen at the school dance in the seventh episode later becomes a recurring character in the second season: Sha Shan, Flash Thompson's would-be-girlfriend.
In Piglet's Big Movie, the episode from the original Winnie the Pooh dealing with Kanga and Roo's arrival and subsequent integration into the forest is adapted in flashback form; however, Tigger is in on Rabbit's initial plot to get rid of Kanga. This creates an inconsistency, not only with the book canon, but with the original Disney canon; in both versions Kanga and Roo were well settled long before Tigger showed up.
In Ultimate Spider-Man, Curt Conners has a recurring role in the first season as a SHIELD scientist. He doesn't become the Lizard until the second season.
James the Red Engine makes cameos in all six episodes of Thomas the Tank Engine prior to "Thomas And The Breakdown Train/Thomas Saves The Day". This causes a continuity error since the following episode keeps the novels' statement of the events of said episode occurring on his first day. Henry similarly makes cameos prior to "The Sad Story of Henry/Come Out Henry", while Thomas himself appears before the events of the Three Railway Engines stories as a result of "Thomas And Gordon" being adapted as the first episode to fit his leading status.
This seems to be a recurring tendency for characters newly introduced in feature length specials. Most seasons produced at the same time will feature said character. The majority of the time the specials are released some time after the season (are a fair number of episodes) have already aired, meaning the character first appears in the TV episodes.
In the first ever episode of Pokémon, Ash catches a glimpse of a large golden bird flying through a rainbow. That bird was only revealed with the arrival of the second generation as Ho-oh, a legendary bird Pokémon; his colors changed a lot since then. It is actually a habit within the franchise to show a new Pokémon specimen in the anime or in movies before it's actually available in the current games. Togepi, Marill (and its pre-evolution Azurill), Snubbull, Kecleon, Lucario and Munchlax are only few examples of this phenomenon.
For non-character examples: the first movie's Big Bad, Mewtwo, uses Shadow Ball, a generation before it's introduced. Likewise, Green from Pokémon Special also had Pokémon who know 2nd generation moves and used them in the RGB saga, again before the 2nd generation introduces them.
Also from the first movie - Ash fights the then-not introduced Donphan during the opening credits and it uses another move from the next generation, Rollout. Neither Donphan nor Rollout were even named in the movie.
When Ash and co visited Virbank City, he checked out Pokéstar Studios and fought Gym Leader Roxie for his eighth badge afterwards. This was all done before Pokémon Black 2 and White 2 came out, which was when Virbank City and everything in it was introduced, at least when it was first broadcast in Japan.
The Best Wishes anime also featured Pokémon from X and Y. Helioptile, Gogoat, and Noivern debuted shortly after the 16th movie in Japan. Also coming along with them was X and Y character Alexa, who happens to be sister of the first Gym Leader in Kalos, and is there to introduce the Kalos region to Ash. Not so much outside Japan, where the first episode with them debuted on X and Y's launch.
The Pokémon Origins special was the official debut for Mega Charizard X, before any press material was released for the new Mega Evolution.
In the Lime-iro Senkitan OVA, characters from the series' direct sequel, Lime-iro Ryukitan X, appear. Major Gamou, lead heroine Tsumugi Shima (and her Raimu), as well as one of the villainesses, Linen (though she's unvoiced), all appear for the first time, not only before their anime series, but before their game was released as well.
At the end of the final episode of Mai-HiME, Arika, the lead of Mai-Otome, runs across the screen in the background.
Also in the second episode you can see a girl who looks almost exactly like Nina sitting in the seat next to Mai and in front of Yuuichi. (She also is in the lineup of girls in the opening credits)
Arika is shown in slightly more detail in the last chapter of the Mai-Hime manga, apparently meeting with some school officials to discuss enrolling.
The first or second English Dragon Ball Z opening had adult/future Trunks in the title slide at the very end, despite him not being introduced until several arcs, and a Big Bad or two, later. Showing up at other points in the intro are Super Saiyan Vegeta and Mecha Frieza (who is getting sliced apart by Super Saiyan adult/future Trunks.) long before their English debuts.
Zone of the Enders: IDOLO was created as a prequel OVA to the Playstation 2 game Zone of the Enders. In it, scientist Rachel Links looks at a Fatal Family Photo of her estranged husband and children, reflecting that she wished she could seem them again. It is a small scene in the OVA, but the full-length series that came after centered on her husband James trying to reconcile with their children and seek her out.
In the Heroes graphic novels, Sparrow Redhouse makes a brief cameo in a season one issue, about two years before her proper debut in the "Rebellion" story arc (which also retconned an unnamed, masked extra from the TV series as being her).
The Protectobots, Aerialbots, Stunticons, and Combaticons in the MarvelTransformers Generation 1 comic first appeared in Buster Witwiky's dream in a UK filler story before their proper debut in the US comic.
This happened to the new Aqualad in Young Justice - the version for the animated series was created first, but his comic-book counterpart first appeared in June 2010. The series premiered January 2011.
In Lilo & Stitch, as Pleakly and The Grand Councilwoman are using the lift to go to Jumba's cell, you can see Dr. Jacques von Hämsterviel in a cell to the right. Hamsterviel would go onto becoming a major villain in the TV series.
What's more, he came out of nowhere, single-handedly defeated the Big Bad (who was whomping two Riders who could singlehandedly destroy a single universe), and then left. The other riders compacted on that with their own Crowning Moment Of Awesome, but still, ain't that application of The Worf Effect taking promotions too far? (As further evidence, when Double joins up for Decade's final battle in the DecadeGrand Finale movie, he's been brought down to saner power levels.)
Double's movie, Double Forever: A to Z: The Gaia Memories of Fate, featured the debut of his successor, Kamen Rider OOO.
Kamen Rider Fourze does the same in OOO's summer movie, crash-landing in the middle of a fight.
Kengo and Yuki also make a cameo in OOO's final episode.
Kamen Rider Wizard appears in Fourze's summer movie, and his human identity Haruto Sohma appears at the end of Fourze's finale.
The Movie Wars series features the Second Riders in various degrees of importance before debuting in their respective series. Both Accel and Meteor appear in The Stinger (Accel does nothing - in fact, we don't even see his Rider Form; we only learn that he's a Rider because he said that "Double isn't the only Rider in Futo anymore" while holding a Gaia Memory- but at least Meteor was dealing with a bunch of escaping Foundation X goons). On the other hand, Birth takes part in the final battle.
And now, Gavan Type-G, the new Gavan from the revival movie, will make his first appearance in Go-Busters.
The obscure made-for-TV film Cucumber Castle, based on the Bee Gees' song of the same title and starring Barry and Maurice Gibb, features an appearance by a familiar-faced child - Andy Gibb, then ten years old.
When Agent Coulson first appeared in Iron Man, he was nothing more than a random S.H.I.E.L.D. agent. He kept popping up in the Marvel films in minor roles, but it wasn't until The Avengers that he became a major character.
Live Action TV
Played with in Witchblade: Gabriel Bowman is first introduced in the third episode of season one (not counting the pilot movie); then, in the second season premiere, which is a same-but-different retread of the events of the pilot, he's shown to have been present at the shootout in the museum, and ends up meeting Sara a lot earlier than he did the first time. Which would make him a kind of Destined Bystander as well.
Cookie Monster actually made his first appearance in a skit featured in The Ed Sullivan Show (which itself was based on an old instructional film by IBM), where he is shown taking a machine apart piece-by-piece and eating it, only to realize that doing so will cause the machine to self-destruct within his body, causing him to explode. And for some reason, this version of Cookie Monster has fangs, while the one in Sesame Street does not.
Several years before he became famous as the host of Double Dare, Marc Summers was a page at CBS. At age 22 in 1973, he got to fill in as announcer on The Joker's Wild for one week.
The liner notes for Guns N' Roses' Appetite for Destruction include the lyric "With your bitch slap rapping and your cocaine tongue you get nothing done", a lyric for "You Could Be Mine" (which was recorded in their next album). Also, the notes for Use Your Illusion I have "Ain't It Fun?", the title of a song they covered in The Spaghetti Incident?.
My Chemical Romance's debut album, I Brought You My Bullets, Your Brought Me Your Love, have the french phrase "Merci pour le venin" written on the liner notes. It is the french title of "Thank You For The Venom", a song appearing on their second album, Three Cheers For Sweet Revenge.
They Might Be Giants' "On Earth My Nina", released on 1999's Long Tall Weekend, was a reversed acapella version of "Thunderbird", which wasn't released until The Spine five years later.
Red Hot Chili Peppers played Fortune Faded live in August 2001, as part of a batch of new songs. A studio version of it didn't appear until November 2003, when it became the new single for their Greatest Hits compilation.
The By The Way sessions demo has since leaked out. The band did not release the song at the time because they felt the chorus melody resembled one by another band. They rewrote the chorus for the Greatest Hits version.
Several years before Jeremy Dawson and Chad Petree founded Shiny Toy Guns, the chorus lyrics of "You are The One" appeared in a trance song called "Neo(The One)" that they produced under the name Slyder, and which appeared in Grand Theft Auto III on the Rise FM station.
A year before Pearl Jam's debut album, Eddie Vedder could be heard singing backup on Temple Of The Dog's self-titled album, as well as getting a full on duet with Chris Cornell on the song "Hunger Strike". Temple Of The Dog and Pearl Jam shared most of the same lineup (and the drummer, who played with Cornell in Soundgarden, would later join the band), and Vedder ended up on the Temple Of The Dog album after auditioning for Pearl Jam.
Da Yoopers had "Cowboy" Dan Collins sing backing vocals on two albums several years before he became an official member.
Shania Twain's first credits were singing backing vocals on albums by labelmates Sammy Kershaw and Jeff Chance in the early 90s.
The live film produced from Michael Jackson's 1988 Japanese performance features Michael performing "I Just Can't Stop Loving You" with one of his back-up singers from the tour - Sheryl Crow, whose fame was still several years away.
The ending theme to Sonic the Hedgehog 3 (1994), whose soundtrack was at least partly composed by Jackson, sounds very similar to his single "Stranger in Moscow", which was composed in 1993 but not released until 1997.
The 1971 album Ram by Paul and Linda McCartney had a ukelele-driven segueway song called "Ram On (Reprise)" on side two. On the fadeout, you can hear Paul launch into a few lines of "Big Barn Bed", which would be the first song on Wings' second album, Red Rose Speedway (1973).
Early copies of Radiohead's Kid A included an extra booklet behind the CD tray as an Easter Egg. Some of the cryptic text included in said booklet turned out to be lyrics to songs that would appear on Amnesiac, which was recorded during the same sessions.
One of Jennette McCurdy's first credits was appearing in the music video for Faith Hill's "The Way You Love Me". Before that, she was a recurring actress on Mad TV.
And speaking of Faith, she also qualifies, as she sang backing vocals on Gary Morris' 1989 album Stones four years before releasing her debut single.
Singer-songwriter Jeffrey Steele's first credit was on the late 80s tribute album A Town South of Bakersfield. He also wrote an album cut for Steve Wariner in 1990 before doing two albums and an EP as Lead Bassist of the band Boy Howdy (who had two Top 10 hits with "She'd Give Anything" and "They Don't Make 'em Like That Anymore"). After they split up, Steele enjoyed a Breakup Breakout as a highly successful songwriter for other artists, most notably Rascal Flatts.
Before Keith Urban charted his first single in 1999, he had a ton of bit parts. Among them were a backing vocal credit on INXS' Live Baby Live (1991); a cameo in the video for Alan Jackson's cover of "Summertime Blues"; co-writing credits for Toby Keith, 4 Runner, and the Raybon Brothers; and a few scattered electric guitar credits (most notably Garth Brooks' Double Live). He also formed a short-lived band called The Ranch which had two low-charting singles and one album for Capitol in 1997.
R.E.M. often played songs live, got tired of them, then returned to them a few years later when they were short of material for albums. There are numerous examples across their IRS catalogue. It happened occasionally at Warner Bros as well.
Kesha's mother, Pebe Sebert, has written many of her songs. But many, many years before that (1978 to be exact), Sebert wrote "Old Flames Can't Hold a Candle to You", originally recorded by Joe Sun and later made famous by Dolly Parton.
About a year-and-a-half before his debut, Eric Church wrote Terri Clark's late 2004-early 2005 single "The World Needs a Drink".
Before his 1999 debut single, Brad Paisley wrote "Another You", a top 5 single for David Kersh in 1996.
In 2004, Toby Keith released a duet with his daughter Krystal on a cover of Inez and Charlie Foxx's "Mockingbird". Nine years later, she began her official singing career on Show Dog-Universal, the label of which her father is president.
Before their debut single came out, Lady Antebellum sang on Jim Brickman's "Never Alone".
Jerrod Niemann, who had a big hit in 2010 with "Lover, Lover", made his first appearance as part of the gang of backing vocalists on Garth Brooks' 2005 single "Good Ride Cowboy" (which he also co-wrote).
Record Producer Michael Knox produced two obscure country albums in the late 1990s (29 Nights by Danni Leigh and Like a Train by J.D. Myers). He had no other credits until 2005, when he became Jason Aldean's produer, a role he has held to this day.
The former album also had one of two early-bird cameos for Big Kenny, later of Big & Rich (his other writing credit that year being a track on The Mavericks' Trampoline).
Speaking of Big & Rich… before they released their debut single "Wild West Show" in December 2003, they wrote "Amarillo Sky" for McBride & the Ride in 2002 (later Covered Up by the aforementioned Jason Aldean). They also co-wrote and sang backing vocals on the album track "She's a Butterfly" on Martina McBride's (no relation) 2003 album Martina.
Before releasing her debut single, Kacey Musgraves sang on Josh Abbott Band's 2011 single "Oh, Tonight".
The playfield for Williams Electronics' Space Shuttle shows two astronauts installing an orbital telescope, six years before the Hubble Space Telescope was deployed.
Long before officially joining WWF as Mankind, Mick Foley appeared in a few jobber matches as Jack Foley (his father's name) as WWF wouldn't let him use Cactus Jack.
Mick's first appearance on WWF TV was as a member of the audience watching the Don Muraco vs. Jimmy Snuka cage match from Madison Square Garden in 1983.
Several luchas appeared on WWF TV in 1997 as part of a cross promotion with AAA. One of whom which was Mascarita Sagrada, who later appeared as part of WWE's short lived midget wrestling division in 2005.
Both of the HardyBoyz wrestled regularly on WWE TV during the 90s as random jobbers before getting properly called up in 1999.
Stephanie McMahon made her first appearance on WWF TV when she was only a child. She was one of the kids in the "Roddy Piper's Trick Or Treat" sketch on Saturday Night's Main Event in 1985. She also made appearances in the late 80s and early 90s modelling t-shirts and baseball caps in the WWF merchandise catalogues.
Ted DiBiase wrestled in the WWF for two years in the 1970's, before returning as "The Million Dollar Man".
Some of his promos featured future stars as well. In one, he offered Linda McMahon $100 get down on all fours and bark like a dog, then decided she didn't deserve the money.
He also paid a teenager to kiss his foot after a match. That teenager grew up to become WWF star Rob Van Dam.
Jacqueline wrestled a couple of matches on Heat against indie wrestler Starla Saxton in 1998. Two years later, Saxton would join the WWE roster officially as Molly Holly.
She also appeared on WCW Monday Nitro as Starla Saxton, before joining the company as Miss Madness.
In 1985-86, a 25-year-old Dean Malenko worked for the WWF as a referee. This was 15 years before he would officially debut as part of the Radicalz, possibly the longest time between cameo and appearance on this list.
In a similar example to the Dean Malenko one above, Teddy Long was a referee for years in WWE before becoming a proper onscreen personality, going from manager to Smackdown General Manager.
Teddy did the same thing in WCW. He started off as a referee, then became a manager.
Melina Perez in her pre-MNM days made two appearances on Raw in late 2004, first in a lingerie strip tease segment and then a limbo segment, about four months before she properly debuted on television.
She was also one of the few who didn't make the cut in season 3 of Tough Enough.
Before debuting his Foreign Wrestling Heel gimmick in 2003, French-Canadian wrestler Sylvan Grenier was supposedly a WWE referee tasked with mediating the rematch between Hulk Hogan and The Rock at that year's No Way Out (which, appropriately enough, was being held in Grenier's hometown of Montreal, Quebec, Canada). This is an unusual example in that Grenier was here referred to by name by the commentary team, and his behavior in the course of the match was actually his Start of Darkness and even carried over to WrestleMania XIX the following month!
In the Yu-Gi-Oh! Trading Card Game, Wattaildragon first appeared as a picture on a scroll in the artwork of Ancient Rules way back in Strike of Neos, over five years before its own release in Galactic Overlord. Its flavor text even makes a reference to "ancient rules" which forbid its capture.
Future Sight is built around these. Most of them preview elements from Lorwyn/Shadowmoor block, from individual cards to the tribal and planeswalker card types.
Spike Drone appeared one set before any other Spikes.
Shield of Kaldra mentions Helm of Kaldra, a card released one set later.
Ravnica block has guilds appearing in flavor text before they actually showed up with cards of their own.
In the third edition rulebook of Warhammer 40,000, pictures of generic Kroot and Necron warriors appear several years before their armies were officially introduced.
Three examples from Disney Theme Parks. Sleeping Beauty's Castle was opened in Disneyland several years before the movie. It's Tough To Be A Bug, starring Flik and featuring Hopper, was introduced at the Animal Kingdom several months before A Bug's Life opened. Finally, Countdown to Extinction featured Aladar and a Carnotaurus about two years before Dinosaur premiered, at which point the attraction was renamed after the movie.
The Transformers Prime did not have any toys until after the Dark of the Moon line has been out for a while. But a few of the major players (Optimus, Bumblebee, Megatron, Starscream, & Soundwave) got each got a toy in the Generations line.
Sunstorm and Acid Storm originally appeared as unnamed Seeker jets in Transformers Generation 1, and didn't get toys and names until the Universe toyline two decades later. There was also a green palette swap of Grapple later named Hauler.
Asagi might be the ultimate example of this. Of course, we don't know if she's ever actually going to GET her own game or if Nippon Ichi is just screwing around.
While we're on the topic of Nippon Ichi, it's probably no coincidence that Makai Kingdom will be getting a PSP remake after Overlord Zetta's cameo in Disgaea 4, which is the first time since Makai Kingdom that he has actually appeared in humanoid form. The new character from the remake, Petta, will appear in Disgaea 4 as Downloadable Content.
The Gekko from Metal Gear Solid 4: Guns of the Patriots and a remix of the game's "Theme of Love" both appeared in Super Smash Bros.. Brawl, which in some regions was out months before the former game was even released. For that matter, the entire Shadow Moses Island stage is a reference to an entire chapter in the game. Interestingly enough, MGS 4 is a PS3-exclusive game, meaning a first-party Nintendo game is promoting a game not available on a Nintendo system.
Metal Gear Acid 2 beat both games by featuring Metal Gear Solid 4 trading cards two years before the game was even released (granted, they were based on the very first trailer that was released).
Metal Gear: Ghost Babel, which was released a year before Metal Gear Solid 2, featured an extra game mode where the player controls a newly recruited soldier who undergoes VR training by having to complete harder versions of Solid Snake's missions in the main game. The name of this agent is revealed at the end to be "Jack", the same name of the protagonist in MGS2.
Cyborg Ninja Raiden played a cameo role in Metal Gear Solid 2: Substance. However, it's not the same Cyborg Ninja suit Raiden wears in Guns of the Patriots, but more of a cosplay of him in Gray Fox's exoskeleton suit from the first MGS.
Galen Marek, aka Starkiller, Darth Vader's secret apprentice and protagonist of Star Wars: The Force Unleashed, made a playable appearance in Soul Calibur IV three months prior to the release of his game. He goes simply as "The Apprentice" in SCIV.
In Space Invaders Extreme (available on both PlayStation Portable and Nintendo DS), Mr. ESC from Exit makes a cameo appearance when you select the Exit option. While Exit was already released on the PSP at the time, and the DS version of the game was already available in Japan at the time, the DS Space Invaders Extreme appearance is a legitimate Early-Bird Cameo in North America.
The Kyo clone Kusanagi initially showed up in The King of Fighters 2002 as an alternate moveset for Kyo, but did not receive a role in the story proper until the next game, 2003.
Nearly half a year before he became the protagonist of his own game Luso Clemens showed up as a minor playable character in the remake of the original Final Fantasy Tactics, War of the Lions, even though the games are on competing systems. In what is either this or an Ascended Extra, Hurdy, a main character from A2, first appeared as an operator of the teleporting services in Final Fantasy XII.
Dengeki Gakuen RPG: Cross of Venus has an actor variant of this trope: being a Massive Multiplayer Crossover video game based on several Light Novels, it manages to get the voice actors of the featured series' anime adaptations to reprise their roles. This includes the voice cast of Asura Cryin'', which adaptation premiered a few days after the game's release.
Dan Hibiki also appears as a random design that was expected to go unused in some old artwork poking fun at SNK's Art of Fighting series. He later became an official, secret character in Street Fighter Alpha.
Balrog and Vega made cameos in Sagat's endings in the first two Alpha games, while E. Honda appeared in Sodom's ending in Alpha 2. All three of them would appear as playable characters in Alpha 3. Fei-Long also made a cameo as a spectator at Dan's stage in Alpha 2, but he wasn't included in Alpha 3 until the console version.
Rolento and Cody made cameos in the first and second Alpha games respectively before they became playable in Alpha 2 and Alpha 3 respectively.
Chronologically, Street Fighter IV is set before Street Fighter III Yun and Yang appear in Chun Li's opening story sequence in the console version. They later appeared as playable characters in the arcade version of Super Street Fighter IV.
The appearance of Alfred the Pilot in Real Bout Fatal Fury 2 was meant to be a tie-in for his own game, a PlayStation-exclusive port Real Bout Fatal Fury Special subtitled Dominated Minds, but since that game was only released in Japan, many people think he was simply a character made up for Real Bout 2. In Hon-Fu's and Yamazaki's endings, the antagonist from Dominated Minds, White, can be seen.
Rock Howard, the protagonist of Garou: Mark of the Wolves, appears in Terry's ending in Fatal Fury 3.
The Oukaou and Nanajin from Wings Of Rean both appear in Another Century's Episode 2, which came out a few months before Wings Of Rean premiered.
Pokémon XD: Gale of Darkness is a third-generation game. It features a non-playable Munchlax and a sorta-playable Bonsly, both fourth-generation Pokémon.
Munchlax appears as a playable character in the original Pokemon Mystery Dungeon Rescue Team games via cheat codes. The player can also get statues of Lucario, Weavile, Bonsly and Mime Jr. placed outside their house.
Also in the original PMD, Munchlax walks through the square as a random event.
Munchlax also appeared in the game Pokémon Dash.
Rock Band 2 had the album release of Shackler's Revenge a few weeks before the album it was on (Chinese Democracy) was released.
Guitar Hero had two of Music/Foreigner's re-recordings of "Jukebox Hero" and "Feels Like the First Time" release before the release of the album "Feels Like the First Time".
Sonic the Hedgehog appeared as an air freshener in the racing game Rad Mobile two months before the first Sonic game.
The tune for "Sonic - You Can Do Anything", the Japanese/European opening of Sonic the Hedgehog CD, was first used as the BGM to Green Hills Zone in the Master System/Game Gear version of Sonic the Hedgehog 2.
The Shadow Androids, artificial clones of Shadow are first shown in Team Dark's ending in Sonic Heroes. They later appear as actual enemies in Shadow the Hedgehog.
Also, from the same game, there's Krunch, a neutral member of the Kremling Krew from Donkey Kong Country. Although he never appeared in another game, nor did he ever seem destined to, his design and attire were based on the Kremlings in the then-unreleased Donkey Kong 64 as opposed to the original SNES trilogy.
Although she did not appear in person in that game, Kazooie was actually first mentioned in the game instructions manual for DKR.
Also, Fake Crash, a joke expy of the main character, first appears after 100% completion in various locations of Crash Bandicoot 3: Warped before his first playable appearance in Crash Team Racing. It goes back further than that: Fake Crash's appearance in Crash 3 stemmed from a Japanese Crash Bandicoot commercial.
Amazingly, this code managed to remain hidden until after the movie came out. Whether or not this subverts the trope is debatable.
The first mission of Rebel Strike is basically the Rogue Leaderbonus mission "Revenge on Yavin" from the Rebels' point of view.
Geese Howard of Fatal Fury fame makes a cameo in the extended ending of the SNES version of Art of Fighting, which was released months before Geese's actual appearance as the True Final Boss in the arcade version of Art of Fighting 2.
Persona 3 Portable features a man drinking at the nightclub in Paulownia Mall. He appears to be Vincent from Catherine. He tells you a bit of a story about how much of a Jerk Ass he is, then points out that it has "nothing to do with your problems" at the end.
Digimon World 3 featured Agunimon, KendoGarurumon, and AncientGreymon in cameo appearances as DNA Digivolutions; all three Digimon would go on to play large roles in Digimon Frontier. However, it's slightly complicated; Frontier wasn't released in some regions, while in Japan, World 3 was released three months into Frontier's run.
The PC version of the The Fairly OddParents game Breakin' Da Rules! features a level where Timmy has to avoid a younger-aged version of Vicky and Tootie's mom, named Nicky here. The character eventually appeared on the show in her adult form, alongside her unnamed husband, in the "Channel Chasers" movie.
The PC port of Halo 2 includes a silenced version of its SMG in a test map. This silenced SMG later went on to be the primary weapon of the player character in Halo 3: ODST.
Lumi, the virtualDistressed Damsel of Child of Eden, previously appeared in Lumines II in late 2006, which also featured "Heavenly Star", the debut song of Genki Rockets, the semi-fictional band that Lumi is the "singer" of.
Modern Warfare's prologue "Crew Expendable" and endgame "All In" featured two Red Shirt SAS members, Wallcroft and Griffen, who were promoted to squad leaders in the MW3 mission "Mind the Gap".
Jin Kazama's Devil form, which became a playable boss character in Tekken 5, first appeared in his ending cinematic from the PSX port of Tekken 3.
Three years before Max Payne came out, the Aesir Corporation's headquarters appeared during the cityscape flythrough in Remedy Entertainment's Final Reality benchmark/tech demo.
In Trinton Chronicles the villains known as Trinity make a minor appearance at the end of Fantasia before becoming the villains of the next story. By that same token, a character from another furry-based game called Arcadia makes her pre-Trinton appearance here before plopping into Trinton Chronicles two years later.
In the very first story in the Global Guardians PBEM Universe, Stone has a short encounter with a tall, athletic-looking older woman in a bar, where the cynical hero is spending time downing whiskey shots. At one point, the woman tells Stone, "I bet you're a disappointment to your mother." Three years and nearly sixty stories later, and Stone encounters the woman again: it was his mother, who abandoned him at an orphanage shortly after his birth.
In his review of Caligula to celebrate 100 episodes, The Cinema Snob had appearances from all of Brad Jones's other characters, including 80s Dan... at least, until Brad pointed out he didn't have an 80s Dan character, at which point Dan faded away into nothingness. A few weeks later, 80s Dan became an official spin-off.
Dug the dog from Up makes an early appearance as a live shadow on a wall in Ratatouille.
In a DVD bonus short for Ratatouille, WALL•E makes a brief cameo as a Mars rover operator. Parodied on WALL-E's website, which shows him hiding in every single past Pixar movie.
There's a similar gag documentary on the Lilo & Stitch DVD - apparently Stitch has been attempting to get a Disney movie since 1937. The documentary shows screenshots from films with Stitch drawn in them.
Up: When Carl's balloon-house goes past a little girl's bedroom, a teddy bear is in the far left corner of the screen. This is Lotso(-Huggin' Bear), who is an important character in Toy Story 3.
In Toy Story 3, one of the posters in Andy's room shows a car that is an upcoming character in Cars 2. Additionally, he has a "Newt Crossing" sticker next to his computer; Newt was a Pixar film that was cancelled in development.
Cars 2 has car-versions of Princess Merida and her family on a glass window in the British pub.
Okuni, Shigeko, Tamiko, and Shu Todoroki in Tokyo Mater.
Brave: There is a bas-relief of Sully in the Witch's hut, for Monsters University. View it here.◊
A statue of a cherub appears in Aladdin 's "A Whole New World" that later shows up in Hercules 's "I Won't Say I'm In Love".
House of Mouse for some reason portrayed Ronno as a fawn instead of an adult deer since Bambi is always portrayed here as a fawn as well. Young Ronno won't make his official appearance in any animated Disney work at all until the release of the Direct-to-Video film Bambi II.
Ralph the Guard, a regular on Animaniacs, made his debut as an unnamed, surprisingly competent security guard in several episodes of Tiny Toon Adventures. Likewise, World's Oldest Woman and Lucky Bob, two characters on Histeria!, made cameo appearances in Animaniacs segments years before their own show premiered. Histeria's version of Joan of Arc (which was actually just a caricature of Shirley MacClaine) also first appeared on Tiny Toons.
In its second season, Marsupilami frequently appeared in The Disney Afternoon's commercial bumpers a year before Disney released his cartoons as part of the Raw Toonage series.
Five years before the first episode of South Park aired, creators Trey Parker and Matt Stone made a short film called The Spirit of Christmas, which was made using construction paper and had prototypical and mostly unnamed versions of the show's main characters. Three years later they made another Spirit of Christmas, this time with the show's main characters properly named, characterised and recognizable, and also added Wendy Testaburger as an unnamed, non-speaking cameo.
The elephants from Disney's The Jungle Book actually all made their first appearances in the 1960 animated shortGoliath II. The designs for the short's titular character and his father Goliath I were even recycled for those of Hathi Jr. and his father Colonel Hathi, as well as the scene where the elephants actually all pile up on top of one another.
The circus locomotive from Dumbo actually first appeared in the Disney animated short The Reluctant Dragon, where he is portrayed as pulling a passenger train (as opposed to a circus train) only to end up in a railway accident while attempting to jump a broken bridge during a thunderstorm. His Reluctant Dragon incarnation looked slightly different than the one in Dumbo: his drive rods are connected to the forward drive wheels, he was longer in appearance, and there was a bell on his roof. However in Dumbo, his drive rods are now connected to his hind drive wheels, he is now shorter and stockier in appearance, and his bell is nowhere to be seen, implying that he was actually overhauled during his repair between the two films.
Bambi also made his debut there, even though his official debut didn't even happen until the year after.
Laserbeak from Transformers Animated actually first appeared in the form of a toy that is packaged in the same blister pack as Animated Soundwave. Laserbeak himself won't appear in the cartoon until season 3.
Snips and Snails from My Little Pony: Friendship Is Magic showed up as thieves in the Flash game Adventures in Ponyville on the Hub's website before their first appearance on the show. The game also showed Twilight as able to grant functional wings with magic, though they were a very different kind of wing (proper pegasus wings) than the ones she gave Rarity (butterfly wings made of gossamer and dew). Discover the Difference, another flash game on the Hub's website, provides glimpses at the beginning of the instrumental version of a Theme Tune Extended, as well as revealing scenes from "Owl's Well That Ends Well," "Party of One," and "The Best Night Ever."
"Kid" from The Animatrix is a cross-medium example. He plays a significant role in the last two movies of The Matrix Trilogy but makes his first appearance in one of the shorts from the animated direct-to-DVD film.
Three more Hanna-Barbera instances: Before being a heroic sheriff on the Magilla Gorilla show, Ricochet Rabbit was an antagonist on an episode of Touché Turtle two years earlier. Later in the 70s, Posse Impossible appeared in the series finale of Hong Kong Phooey before getting their own segment three years later on CB Bears. And in 1959, lugubrious hyena Hardy Har Har appeared in a Snooper and Blabber cartoon before being paired up with Lippy the Lion three years later.
Terrytoons had three characters in their Deputy Dawg show that spun off into their own series. A little blue space alien became Astronut, a Russian mouse named Mischa became Macon Mouse, and the Long Island Duckling became Duckwood. Astronut was paired with a human named Oscar Mild, Duckwood was paired with a con-artist mule named Donkey Otie, and Macon Mouse was among the gang in Possible Possum.
In the Futurama episode "I Second That Emotion" Leela's parents can be seen in the background among the mutants in a few scenes, they would be properly introduced two seasons later.
The Venture Bros. uses this form of the trope regularly. Many easily-missed background characters gain major plot relevance down the line. Sometimes it's only a few episodes later (such as the Investors appearing in the background of an episode before their official introduction,) while other times it's many seasons later (such as August St. Cloud, who was a frequent background character dating all the way back to season 1, but wasn't officially introduced until season 5.)
A few songs in The Magic Adventures Of Mumfie came out on CD and casette before they appeared in the show, with "Home" and "Real Eel Electricity" being released the earliest. All songs from the show's CD after "Ocean of Sleep" are also this trope, as when the CD was released, the episode featuring the Pirate Song would air a week later.