Non-Indicative First Episode

A first episode of a show that is flashier than the rest of the series is an accepted practice, since it's supposed to wow you and pull you into the story. Even if much action doesn't occur, the timing and budget of the episode is noticeably good. These differences are accepted and even encouraged. Might also be a Pilot which differs significantly from the series due to Executive Meddling or whatnot.

However, if the first episode sets a fanciful creative premise but the later bits of the story clearly show a shove back to the reliance on tired subplots (or even a Genre Shift), the audience can feel unfairly fooled or betrayed. This is often indicated in the Second Episode Morning.

Should hopefully not be coupled with a following Off Model episode. Contrast with Innocuously Important Episode.

Anime and Manga

 * Coyote Ragtime Show is an indicative example: The first episode: Female detective and a local ditzy blond cop are on the trail of a notorious criminal who's hiding out in a prison. The rest of the series is from the criminal's point of view.
 * The first episode of Naru Taru is very lighthearted and relaxed. The rest of the series... not so much.
 * Futakoi Alternative opens with a fast-paced, manic and comedic first episode. The rest of the series is comprised of more gentle Slice of Life episodes.
 * Genesis Climber Mospeada has a space battle opening that introduces an entire series cast aboard a Transforming Mecha carrying warship on its way to a battle. The ship is destroyed, and the lone survivor must pick his way through Scavenger World, meeting the rest of the real cast one by one -- working through a Debut Queue.
 * The Melancholy Of Haruhi Suzumiya starts with "The Adventures of Mikuru Asahina", a painfully low-budget student film that combines Stylistic Suck with as many clichéd anime genres it can think of (Magical Girl shows, High School comedy, Shojo romance, etc.). However, it's actually Foreshadowing several key plot points in the real story (which starts with the next episode), with the brief lapses in the Masquerade serving as plot hooks.
 * The chronologically first episode (which you'll likely see if you're watching them online) is even worse. It's painted out to be a typical high school anime. Stick with it. It gets much better.
 * The series is genre busting anyway. There are episodes that feel like a typical high school anime in there.
 * The first two episodes of Earth Maiden Arjuna make it look like a Magical Girl series, even though it's really more like a serious version of Captain Planet and The Planeteers.
 * Soukou no Strain opened like a sweet, idealistic school show with Humongous Mecha, then took an abrupt left turn when half the cast died.
 * The first episode of Now and Then Here And There makes the show look like a kid's story about the typical energetic shonen protagonist who has adventures in another world. In the next episode he's captured and tortured nearly to death...and then It Got Worse.
 * The first episode (actually, the first and second episodes, fused into one one-hour special) of Gintama deserves special mention -- if only because it's a filler episode. There's a reason why fans will tell you to "Skip to 3!" and it's not because of hopscotch, people.
 * The first few episodes of Chrono Crusade make the show out to be a fairly breezy comedy with pretty nuns and a friendly devil. Then it gets darker and darker until.
 * Murder Princess is an example where the first example is darker than the rest of the series.
 * Heroic Age's first episode is about a lone teenager stranded on a planet, raised by computers, and contacted by other humans. It quickly turns into a space battle anime.
 * The first episode of The Tower of Druaga: The Aegis of Uruk is an out and out parody of fantasy videogame and anime cliches..
 * Lucky Star admittedly does this with their first episode, misleading many viewers curious about its Surreal Theme Tune on whether or not this is actually a series about food.
 * The first episode of Najica Blitz Tactics features plenty of lesbian behaviour, implying there might be more in future, especially between the two protagonists. Unfortunately, there wasn't.
 * From Eroica With Love at first appears to be a typical shoujo manga, about a Power Trio with Psychic Powers, one of whom is accused of being the Gentleman Thief Eroica. But it's really an action packed James Bond Spoof, with the two leads being Eroica and "Iron Klaus".
 * That's because it was originally going to be about the Power Trio, until the author decided Eroica was much more interesting and changed the focus.
 * Telepathy Shoujo Ran hints at becoming a rather dark affair in its first episode. The opposite is the case, especially since Midori's Heel Face Turn occurs very early in the series.
 * Toward the Terra's opening few episodes would not lead one to expect an epic Space Opera, even with the opening.
 * Both Fullmetal Alchemist animes pull this one. Both start with flash-forward stories and do not explore Ed and Al's origins--or the series-defining dark themes they bring with them--until later.
 * The original series kicks off with a two-part adventure where Ed and Al wander into a town and discredit a false prophet. The new series begins with a filler story which is basically pure action, involving an evil ice-using alchemist. The former show's premiere makes the show seem like a Walking the Earth affair with Ed and Al stopping bad guys at different Adventure Towns each week. The latter show's premiere makes it seem like a straight-on action Shounen. Neither is entirely true (though the story has some elements of all these tropes.)
 * The manga did the same, with the first two episodes of the first anime being based on (and expanded from) the first two chapters of the manga. (Brotherhood doesn't visit this story until its third episode, after the backstory has been delved into somewhat.)
 * Ga Rei Zero begins by introducing an elite unit of spiritual monster slayers in a flash-forward. . Then, in the second episode, we get to see the actual main cast fighting the aforementioned swordswoman. Then we rewind and the story begins for real.
 * The first chapter of Billy Bat makes it appear the series will be a film noir parody with a cast of animals. Halfway through chapter two, it's revealed that this is a comic within a comic, and its creator is the real main character.
 * The first episode of the Berserk anime is chronologically set after the events of the rest of the series, in which Guts has already become the one-eyed/one-armed wandering mercenary he is known to be. The rest of the series covers how he got to be that way.
 * The DVD box art combined with the first episode of the anime Gungrave makes you think this will be a Grimdark show about an old lone gunman fighting evil, right? Guess what, the majority of the series from that point on is a giant flashback that shows how two small-time thieves rise up through a mafia-like organization to the point where it reaches the time of the first episode.
 * The first few pages of Tnemrot make it look like it's about the main character surviving in an apocalyptic wasteland Twenty Minutes Into the Future. Then he's captured and we see it's Pokemon with real people.
 * The first two-and-a-half episodes of Puella Magi Madoka Magica make the series look like a Magical Girl series with Slice of Life. That's half-correct. Though to be fair, the scene with the witch's barrier right at the end of episode 1 makes it clear this is not your usual happy fun time show...
 * Rumbling Hearts begins as a sweet, almost saccharine story of young lovers coming together despite awkwardness and misgivings, promising to overcome their initial mistakes. And then in the last five minutes of episode two, it gets worse.
 * The first episode of Cubex Cursedx Curious made it look like a cute, lighthearted Slice of Life show with a supernatural twist. Halfway through Episode 2, that perception goes to hell.
 * The very first episode of Magical Girl Lyrical Nanoha is chock full of magical girl cliches. The deconstructions start immediately in the second episode.

Live-Action TV

 * The first episode of Star Trek the Next Generation had a very "Look what we can do now, bitches," feel to it. By contrast, the visual effects and plots on the next three episodes wouldn't have looked out of place on the original series (indeed, the very next episode was a rehash of another, rather better, episode of Star Trek the Original Series.)
 * Even better examples in the Star Trek spin-offs:
 * The opening of the premiere episode of Star Trek Deep Space Nine begins with a flashback to one of the biggest battles in franchise lore (indeed, the most detailed canon depiction yet) and then promptly goes...to a broken-down space station the Federation recently inherited. It then looks like that the series is going to be about the Federation dealing with cooperation with the relatively primitive Bajorans, who were just liberated from occupation by another alien race. But then near the end of the episode, all of a sudden this wormhole starts to open up literally right next door....
 * To make the surprise even more complete, the episode originally aired with an opening sequence sans the now famous wormhole
 * Star Trek Voyager begins with scrolling text about the state of the Maquis, a group of rebels fighting the Federation. The USS Voyager gets ready to track down a particular group of these bandits and retrieve a Federation officer working undercover. Then both the Voyager and the bandits get suddenly transported to the literal other end of the galaxy....
 * The Invisible Man series had a pilot with a very distinctive style of cinematography and a variety of settings and camera angles thrown in that give it a visual style that is very distinct (and probably very expensive) from the rest of its episodes. It was also a lot more comedy oriented than the rest of the series, including stuff like a scene with Darien and Hobbes getting into a gunfight with a couple of Canadian terrorists with the latter dual wielding assault rifles and screaming "SCREW THE EXPOS!".
 * The pilot of Airwolf is much more cerebral and slower-paced than future episodes would be. Future villains would rarely be on par with Doctor Moffet, who could've easily carried a permanent Big Bad status if not for being killed off. This effect becomes even more pronounced after the first season, when the show moved away from its down-to-earth commentary on the Cold War.
 * In the Upstairs Downstairs pilot, a lot of things go just as they go in the show - but Alfred is a creepy, biblically-speaking maid-harrassing implied perv. In the actual show he didn't speak any too funnily, and turned out to be gay.

Web Original

 * While not a show, the first blog post of Just Another Fool is entirely different from the rest of the blog; it's a meandering ramble about Logan's watch, which is not related to the rest of the story, in the slightest.

Western Animation

 * The two part pilot for The Dreamstone is somewhat more actionized than the rest of the show, the heroes and the mystical background of the Dreamstone are given more serious Character Development and even a death occurs (a couple more are teased to emphasize the danger of the mission). Afterwards the show quickly downgrades to a Road Runner vs. Coyote cartoon, the focus more on the Urpney's slapstick or the cutesy goings on of the Noops. In addition Rufus, who was the main protagonist of the pilot, is demoted in favor of making the Urpneys Villain Protagonists.