In a broad sense, trailers and promotional photos are often taken from pilot episodes and dress rehearsals, a point at which not everything has been finalized even though a series may be picked up for a full series. The set may be different, there may be different actors and some of the plot lines or segments seen in a promotional trailer may air only in a preview commercial promoting the show itself, and never seen by viewers in any episode aired.
Bravo is notoriously bad for doing this with their reality TV shows. Misleading episode descriptions, cut n' paste editing, mismatched dialogue—they've used every trick in the book.
Cracked .com has this trope listed as #1 of the "5 Cheap Tricks TV Shows Use To Keep You Watching" found here.
Just about everything Judd Apatow's involved with. The trailer for Freaks and Geeks pushed it as an uplifting high school drama with scenes like Lindsay telling Nick that he "just needs to work hard and believe in himself" if he wants to be a good drummer (never mind that the corresponding episode completely subverted that). Meanwhile, the trailer for Undeclared made it seem like a televised American Pie set in a university environment. While, more recently, the trailer for Girls made it sound like a Generation-Y manifesto (like the F&G example, this was done by taking a line from the show's main character completely out of context and neglecting its later subversion).
Nowadays, "On the Next" TV trailers will often include footage and plot points that don't actually appear for several weeks yet. This is egregious in Prison Break-style shows with heavy continuity, as it can give the impression of the story progressing more quickly than it really does. Heroes is a major offender here; for example, it incorporated material from the entire first season into the trailer for the second episode.
Smallville is a worse offender. There have been several trailers that have cut one line of dialog into clips from several seasons past. The trailer for the seventh season finale was entirely a clip of Lex Luthor looking at the Fortress of Solitude. Not only was this teased two weeks previous, it was cut entirely from the episode it was shot for. Ironically, when a recent episode decided to reveal the adaptation of the Superman Suite, many fans believed they were being played (due to the show's "No Tights, No Flights" rule which is the whole reason why it took eight seasons to make something remotely close to Superman's tights).
Nearly every show nowadays does this after the season premiere and the voiceover usually explicitly says "This season on..." whichever show you happen to be watching.
In its early days, Sky One used to have a single set of clips for an entire series which they played every week, regardless of which episode was to be shown at the advertised time. The result being of course that the episode usually had nothing to do with the clips you saw in the ad.
Promos for the episode "The Well" promised that it would be a tie-in to Thor: The Dark World, and even showed footage of Thor, Asgard, and the Dark Elf ship that attacked London in the film. Not only did none of these characters or vehicles appear at any point in the episode, but the "tie-in" itself consisted of the agents cleaning up debris from the battle in London before immediately moving onto a completely unrelated plot about a Norse hate group. A LOT of people were pissed about this episode.
The TV spots for "The Bridge" made it seem like Melinda was being cold to Sixth Ranger Mike, telling him "You shouldn't be here." The clip was spliced together from two entirely different scenes, and at no point in the actual episode is Melinda ever rude or dickish to him.
Airwolf: One episode preview has Dom complaining about how low they're flying, followed by a cactus being splattered against the window. The cactus was removed from the actual episode.
American Idol: On one Next Episode Preview, it showed Barney the Dinosaur auditioning for a brief couple seconds. Needless to say, when he didn't appear in the next episode, some were thoroughly disappointed.
America's Got Talent: Usually includes a teaser featuring a mediocre contestant crying during an elimination round, bookended with clips of the judges admonishing someone. 95% of the time, the contestant is actually crying Tears of Joy because they're so happy to have made it through.
Teasers for upcoming episodes also sometimes feature contestants who never appear or only pop up weeks later.
A trailer for an early episode where Beka thinks she's found a way to Tarn Vedra plays up the Vedran aspect and makes it look like the plot is that the Vedrans are a sinister group tormenting the crew. In the episode they never actually reach Tarn Vedra and all of the problems they had came from Beka overdosing on a stimulant.
A mid-series episode has Dylan jump into a ship with its crew of one to get him out of a hairy situation. The bad guys come gunning for him and the captain says "do you have a plan B?" Dylan confidently replies "I always have a plan B. You were plan B." In the promo for the episode the question "do you have a plan B?" was followed by Dylan worriedly saying "You were plan B." Same line but different message.
Angel: In the middle of the Jasmine arc, an On the Next centered around Angel and Fred kissing, with the announcer going on about how the crisis will drive them together... in the actual episode, the kiss turns out to be a Fake-Out Make-Out and no romance comes of it.
An earlier trailer showed Darla, Angel chained against a wall, Angel jousting and the implication that this was all centered around her machinations. While those things actually do happen, the joust is for a minor character and by the time Angel ends up on that wall it's actually part of a test to save Darla who is dying of disease.
Anthony Bourdain: No Reservations: Season 5 was bloated with this. Every episode pointed out that he was going to have a bad time at his destination but on the actual show, it was always just a minor moment of discomfort that took place in the first half of the episode, surrounded by Tony loving the place.
Arrested Development: Played with, in which the clips at the end of each episode were almost never actually featured in the next, but sometimes became important in their own right.
Also, in one third-season episode, trailers advertised 3-D, that "the shocking final moments" would be live, and that "one of these people will die". Well, they did come through! ...In underwhelming ways:
On the 3D, it lasts for about one shot.
The old racist lady dies. The narrator made a point to mention it.
For the final scene, only that one 5 second part was done live.
Sadly, this trope may have led to the show's cancellation. The original TV-spots didn't quite present the show as they should have.
Trailers for the Arrow episode "Sara" made spliced two different shots from different scenes in the episode together to make it look like Laurel blames Oliver for her sister's death and threatens him with a gun. Not only does this never happen in the episode but despite the trailer's implications Laurel never once thinks Oliver is Sara's killer or involved somehow.
Babylon5: The trailers for each new episode of this show - reproduced on the dvds for your viewing dissonance - always tried to make it sound much more of an action 'n' explosions show than it actually was. Sometimes this almost worked, most times you'd wonder if it was the same show, and sometimes, you'd wonder if if was the same universe.
Battlestar Galactica (Reimagined): An interesting case: the trailer featured D'Anna telling Roslin that she's the final Cylon who has yet to be revealed. However, the cut revealing who she was talking to caused some speculation that Roslin actually wasn't the person she said it to. It turned out D'Anna was talking to Roslin, but was just playing a prank on her. Of course, had Roslin been the final Cylon this would have been a major case of both Trailers Always Spoil and Lying Creator (as showrunner and producer Ron Moore had officially declared that Roslin is not a Cylon).
Another episode's trailer has Tom Zarek state that Saul Tigh is dead and Bill Adama is facing execution. In the actual episode, both men were alive and well and Zarek was only lying to Roslin as part of a last-ditch gambit when his mutiny was falling apart.
Being Human: An On the Next trailer for this show showed (in order): A woman looking into her hand mirror and realizing that Mitchell has no reflection, A Torches and Pitchforks mob of neighbors shouting and throwing things at the outside of the main characters house, and George saying "We were kidding ourselves to believe we could fit in here. We.. are MONSTERS!". The not so subtle implication was that the Vampire, Werewolf and Ghost would all be outed and they'd have to deal with the ramifications of that. In the episode itself Mitchell was accused of pedophilia because the woman's son accidentally borrowed a vampire porn/snuff film from him. The Masquerade remaines unbroken, except for the boy and his mum finding out about Mitchell at the end before promptly leaving and telling the neighbors that they made a mistake.
The 2009 Christmas special featured a clip of Leonard's mother kissing Sheldon as if it were a huge plot point. In the actual episode, she was drunk and curious. It was more of a gag than anything.
Promos for the third season finale did this as well. They had the announcer ask what the guys would do for the finale with Sheldon saying "We're going to blow up the moon." In the actual episode, Penny's date asks if that's what they're going to do and Sheldon actually says "You'd be crazy to think we're going to blow up the moon."
The trailer for a recent episode had the narrator announce "this is the episode you've been waiting for", then showed scenes of a hot woman in the guys's apartment and a scene of Sheldon giggling, making it look like he was attracted to her. Needless to say, or it wouldn't be in this category, Sheldon had no romantic interest in the woman whatsoever (she was a fellow physicist he invited to stay with him) and the giggling was taken out of context. (Said woman did have sex, but with Leonard, and later, Raj).
For whatever reason the Australian promos all try and play the episodes for drama. Several treat Sheldon's "we can't be friends anymore" moments as shocking swerves that will change the show forever instead of a one-time gag about the roommate agreement that barely factors into the plot.
Birds of Prey: On The WB in 2002, this show kept employing this trope week after week to the point where it actually played a large part in causing the show's demise in the eyes of many critics, in retrospect. To elaborate, the show centered around the full-grown daughter of Batman and Catwoman fighting crime alongside Black Canary and the former Batgirl, Twenty Minutes into the Future...or today (the show was kinda vague about it), with guidance from Alfred, while a manipulative Harley Quinn hid in plain sight, and plotted to avenge The Joker by getting back at the Bat-Family. Cool...except that the show kept promising "Next week...*cut to silhouetted images of Batman or a Batarang on a wall*" and promising that Batman would be returning to Gotham, with much hype and fanfare...and then every week it'd turn out that the trailer had just lied. The show employed this sooo much, and so shamelessly, that viewers en masse got sick and tired of being lied to every week, and the vast majority stopped watching by midseason. The ratings got so abysmal that the show was suddenly yanked off the air without warning (not that anyone was watching by that point), though The WBdid air the already-filmed season finale as the Grand Finale a few months later.
Bones: The Verizon FiOS info for one particular episode of this show states that the cast is working undercover at a bar to help solve a case; additionally, ads hyped the fact that Booth and Bones would wind up in bed. Actually the episode was All Just a Dream because a comatose Booth was hearing Bones read the rough draft of her latest novel and his mind was inserting his friends as various characters, including himself and Bones as a Happily Married couple.
The trailers were, in fact, just as deceptive for that episode.
FiOS's info is at it again: All of Tom Hanks' appearances on talk shows in March 2010 are descibed as "Toy Story 3's Tom Hanks" even though he's doing PR for The Pacific while Toy Story 3 doesn't bow until June and never gets mentioned. Clearly, FiOS' info writers know what their viewers really like to watch.
Breaking Bad had an in-universe example in one episode. Jesse goes off on a rant about how frozen meals never look or taste as good as they do in the commercials or on the box, and asks "Whatever happened to truth in advertising?"
Buffy the Vampire Slayer: At the end of a season finale, there was a long preview hyping the next season's premiere, saying that Buffy would face her deadliest, strongest, most legendary foe ever... Dracula. The hype blitz continued during the entire off season, with every Buffy rerun containing a promo for the Buffy vs. Dracula showdown, commercials for it even ran in unconnected commercial spots, often during primetime. In all, it was built up as Dracula obviously being the Big Bad for the coming season, or perhaps even multiple seasons, so epic was the ad campaign for the upcoming meeting. When the episode finally came... it was a one-shot, essentially a gag episode, where Dracula's arrival was treated largely as a joke and Buffy doesn't actually defeat him, but essentially mocks him into laying down and playing dead. He was never heard from on the TV series again, reappearing only in comics once or twice. Hard to say whether it was just a really deceptive ad campaign or a rather mean-spirited Take That.
Burn Notice: Australia's Network Ten does this with all its commercials. Another example is its adds for this show, which always end by asking if this is the episode where Michael's plan fails, followed by footage of an unrelated car exploding from later in that episode.
Caprica: In the midseason finale, Amanda Graystone attempted suicide by jumping off a bridge. In a trailer for the next half-season, her husband Daniel was seen angrily throwing a holographic avatar of Amanda to the couch and shouting "I want you to be real!". The obvious interpretation was that Amanda had actually died and Daniel was trying to create a Replacement Goldfish (as had already been successfully done with his daughter Zoe and Joseph Adama's daughter Tamara), making this a case of Trailers Always Spoil. Except, when the half-season aired, it turned out that Amanda had survived but was estranged from Daniel, and the Amanda avatar was created to test the Replacement Goldfish program before mainstream use.
Castle: In the previews for the episode "Nikki Heat", we see Castle hold a diamond ring in a box and ask an unseen person "Will you marry me?". In the actual episode, Castle is just giving Ryan advice on how to propose to his (Ryan's) girlfriend.
Cold Case: Possibly overlaps with Tonight Someone Dies: one episode had a plot where one of the detectives had gone missing and the others were looking for him. The trailer had a scene where they encounter a body, with one of them pulling away the sheet and reacting appropriately. Of course, it wasn't their friend, but a homeless guy who had jumped off a building, and had no importance to the plot whatsoever.
CSI NY: CBS had a promo for the episode "All In The Family" with Danny shielding a woman from another person with a gun, then the screen cutting to black and the sound of a gunshot. In reality, he managed to convince the person with the gun to not kill him or the woman he was protecting (Rikki Sandoval, mother of Reuben, the boy who was killed) and no one was shot. The gun sound was in fact a sound effect added in.
Dawson's Creek: A Brazilian cable TV trailer for one episode had Dawson saying the words I love you to Pacey, then leaning towards him. The voice-over even joked about Dawson borrowing some of Jack's genes (all the trailers in that network were really humorous and tongue-in-cheek) It turned out that episode had Dawson and Pacey reading one of Dawson's movie scripts, and he's not leaning towards Pacey, he's just reaching for the script. Though the reading the script scene was the first one in the episode, so for half a minute you thought Dawson was really professing his love for Pacey.
Deadliest Catch: During the 2009 opilio crab season, the preview for the next episode of this show included the captain of the Cornelia Marie calling for a Coast Guard helicopter, leading the viewer to assume an emergency. The reality? The captain was calling to ask what the ice conditions were like while preparing to leave the harbor.
Anything involving Capt. Phil and emergencies is now Harsher in Hindsight now that he's dead, although that happened while he was in port.
Degrassi: Teen Nick mastered this trope for promos. Season 10 has a lot of blatant examples. Fiona standing at the edge of the roof (is not a suicide attempt, she just finds it dramatic to think on the roof). Anya's pregnant (no she's not), Clare's getting a boobjob (no she isn't). In the final episode of 2010, they showed Jenna looking like she was in labor at a party(she wasn't) Then they continue with this in the trailers for the 2011 premiere, as if everybody forgot what the actual situation was. The best being an ad playing on Ship Tease, with the two actors practicing on the copier for the show. That couple never happened in the series, ever.
Don't forget when they implied that Declan and Clare would hook-up (it turned out to be All Just a Dream).
Design Star: It is pretty much a guarantee on this HGTV reality show that whoever looks like they are in trouble at the end of the episode is fine, and vice versa. For example, in a recent episode, the judges say, "This is not your best work" and it cuts to a dismayed-looking Karl. In the actual episode, the criticism is directed at Kellie, who ends up going home, and Karl's look is his stunned relief in having been declared "safe" for the next week.
Desperate Housewives: One preview ended by promising "a twist so shocking, we can only hint at it," followed by the first line from the chorus of Kate Perry's "I Kissed a Girl": "I kissed a girl, and I liked it." The obvious implication was that one of the housewives would become a lesbian, or at least question her sexuality for a while. The episode did at least follow through with two lengthy girl on girl kisses, but it was part of a minor comic relief subplot where Susan's lesbian boss mistakes her for being interested, and the misunderstanding is entirely cleared up at the end never to be brought up again.
Dexter: A trailer for one episode asked "Which one of these suspects is the ice truck killer". The "suspects" seem to have been chosen completely at random, two are very well established characters who couldn't be the killer barring some bizarre Twist Ending. Another has the notable handicap of being dead. The process of elimination would seem to point to the fourth suspect who, having been only introduced in the previous episode, seems the natural candidate anyway, but since whoever made the trailer has clearly not watched a second of the show it would probably be hopelessly naive to think so. Another one asked if this was the episode were Dexter would be found out, which only did not happen, but had absolutely nothing to do with the plot.
Doctor Who: A trailer for the 2007 episode "The Family Of Blood" showed John Smith getting married and having children. In the episode itself, this was just a Last Temptation to the life he could have if he didn't turn back into his usual self.
The BBC One trailer for "The Waters Of Mars" ends with the Blatant Lie of someone knocking four times just like The Prophecy said, in the actual episode however, it was Lampshade Hanging and the Doctor stopped the villain from knocking a fourth time. The trailer repeated the fist knock.
The ad for "The Doctor's Daughter" puts a great deal of emphasis on a blonde girl backflipping through a row of lasers. The scene was actually a three-second filler with no real importance to the plot (except to further showcase the amazing talents of the Doctor's offspring.)
The Australian trailer kept repeating "Father and daughter REUNITED!", even though Jenny was actually a newborn clone who took her first breaths in the episode. (May also be a misunderstanding of the fact that the Doctor's original companion was his granddaughter.)
Let's not get started on "Turn Left"; let's just say that all the Doctor Who trailers tell us these days is the title of the episode and a few big shocks that WON'T be happening in the episode.
The Sci-Fi trailer for "Evolution of the Daleks" showed the Doctor standing below a hovering Dalek urging it to kill him followed immediately by a shot of someone standing in the same place, in the same position (arms spread, looking up) being blasted by the Dalek. Of course, this wasn't the Doctor but a secondary character, though you couldn't tell because of the "glowing skeleton" effect that victims of a Dalek blast get in the new series. Anyone watching the trailer would swear the Doctor was just executed.
Suffice to say, no one was really surprised when the ads for "The End of Time" featured Wilf ominously informing the Doctor, "The Master is going to kill you!"... and in the actual episode—guess what?—he didn't!
We can't even trust promo shots of Doctor Who: almost all the photos of the Eleventh Doctor's companion Amy Pond showed her wearing a police woman's uniform, leading many to believe that that would be her job; turns out she works as a kissogram, and the uniform was just a costume she switched into when the Doctor showed up in her house.
The trailers for "The Almost People" suggested that Ganger!Doctor was a villain, when in reality he was generally good and helpful throughout the entire episode, even pulling a Heroic Sacrifice at the end.
Season 7 trailers showed a clip from Asylum of the Daleks with Rory surrounded by a group of blown up Dalek shells, leading him to ask "Who killed all the Daleks?" Implying this was the end of the episode. It wasn't, it was only the half-way point. They were merely half-active and insane by Dalek standards.
The preview trailer for Series Six (played at the end of the 2010 Christmas Special) has two examples: a shot of three Nazis bursting into a room while one episode did take place in Nazi Germany, this scene never occurs, and a naked River Song winking at someone (presumably the Doctor). Again, no sign of that anywhere in the new series.
The trailer for "The Day of the Doctor" has the War Doctor's line "Great men are forged in fire. It is the privilege of lesser men to light the flame." In this context, it makes the War Doctor sound villainous. In the episode proper, we learn he's referring to himself as the lesser man, and the Tenth and Eleventh Doctors as the great ones.
In the "next episode" for the season 8 finale, we hear Clara say "I am not Clara Oswald. Clara Oswald never existed!" implying a rather dark twist. She was merely trying to stall for time against the Cybermen by claiming to be The Doctor. There very much is a Clara Oswald.
Don't Forget the Lyrics: FOX's promo monkeys tried to make a contestant's brief moment of discomfort on this show much more dramatic than it actually was. (Source)
And also promoting the same show, they managed to combine this with Trailers Always Spoil: The promos said that a contestant would win more money than anyone else, and said contestant only actually tied for the biggest win.
Eastenders: During the early 00s, this British Soap Opera featured a number of intentionally misleading trailers. For example, one suggested that Saskia would kill club owner Steve; when the actual episode rolled around, the exact opposite happened. Much later, after Matthew was framed by Steve for Saskia's murder, a specially filmed trailer suggested that Matthew would get his revenge by setting up explosive death traps — in reality, his actual revenge plan was slightly less violent.
There was an episode of Elementary about an explosion in an office caused by a bomb that was planted four years earlier. An Australian promo made it sound as if Barack Obama was involved and hinted that it may have been an attempt to assassinate him before he became President, when in fact he only played an incidental part in Sherlock Holmes' deduction of the bomb's age.
ER: There is a preview for one episode where a main character seems to suffer a very serious heart attack, with ominous music and worried onlookers. In the actual episode it turns out to simply be gas.
Eureka: Sci-Fi Channel actually used expectations about never trusting a trailer to its advantage for the fourth episode of season three, and at the same time did slip in a little bit of a lie. The trailer proclaimed "One of these people won't make it through [the episode]", including flashing up a character we'd never seen before, clearly a one-shot throwaway character, using your expectation that they threw him into the preview to be technically correct when one of "these characters" didn't make it through. Well, he didn't. But neither did Nathan Stark, series regular.
Everybody Hates Chris: Did this all the time in the later seasons. They weren't even subtle. No editing, just stuff that didn't happen. One episode trailer had Drew in a school talent show, getting booed off the stage and people throwing things at him. Never happened, not even if a dream before hand about how things might go. He just showed up and rocked.
Glee: Does this a lot by leaking songs for the upcoming episodes...reading too much into the lyrics and what they may or may not indicate about your favorite couple is not advised.
Gilmore Girls: A season four episode featuring Rory and Paris on Spring Break had a promo from TheWB which almost asserted that they would become a couple during a Sweeps Week Lesbian Kiss scene and managed to get a New York Post writer to write a hilarious and badly-researched article dissecting said promo and getting most of the sexualities of the characters all wrong. In reality the kiss was Played for Laughs (Paris just wanted to experience Spring Break at its most heightened absurdity, and Rory stumbled around confused after it happened).
Go Girls: A trailer for one episode of this New Zealand TV show has a main character being told by her boyfriend that she's fat, ugly, and that he's gay. In actuality, this was a daydream of what she was expecting him to say— what he actually does is ask her to marry him.
Grey's Anatomy: In the trailer for the fifth season opener, Nurse Rose told Dr. McDreamy that "I'm carrying your child." In the actual episode, she immediately follows those words with an admission that she was only kidding.
And in the trailer for the seventh season finale, Meredith walks in on a cleaned-out bedroom after having a fight with Derek, during which he said he couldn't live with someone who'd screwed up his Alzheimer's trial. In the actual episode, the room isn't even Derek's, and Meredith actually asked that character to move out earlier in the episode.
The trailer for a late-tenth season episode showed Burke was returning, making it look like he was still in love with Cristina and wanted her to run away with him. In the actual episode he's actually offering her to take over his job as he's retiring.
Hell's Kitchen: A trailer for one episode of Season 4 did a rather spectacular version of this. The trailer showed that one chef sliced off a portion of his thumb, the team couldn't find it, and mentioned that two professional critics were attending that night's service - with the narrator all but saying that the severed portion of finger would end up on a critic's plate. As it turned out, the finger incident happened in the first part of the show, and was already resolved by the time dinner service rolled around - there was never any risk involved.
The trailer for the final episode of Season 1 featured a clip of Michael yelling "Piss off!", but it was almost made to look like he was fighting with Ralph; when the episode actually aired, it was revealed that Michael was simply imitating Chef Ramsey's mannerisms, and Ralph was laughing along with it.
Season 5 does this a lot. Near the end there's a cliffhanger that's resolved immediately the next week.
Any time you see an ambulance or fire engine in the "Next on". Expect it to be either A. a complete over-dramatization of something minor (with no ambulance or fire engine in the actual episode) or B. part of a challenge.
One episode made a big deal out of the Red Team freaking out over some blood, making it look like somebody got badly injured. In the actual episode, the blood came from a cow carcass they were carrying.
Hercules: The Legendary Journeys: Late in the run of the show, the trailers practically guaranteed that a particular episode was the finale of the series. Turns out Hercules did retire...for about five seconds.
Home Improvement: During its last few seasons, this show was notoriously misleading with its advertisements. In the season 6 premier, Jill catches her her oldest son, Brad, in a compromising position with his girlfriend Angela. The advert for the episode shows the pair getting caught in the act and Jill asking, "What if Angela gets pregnant?", followed immediately by a glimpse of Brad's serious expression — and a shocked look from his mother (heavily implying that a Teen Pregnancy plot is about to unfold.) The reality? Brad and Angela never actually have sex in the first place, Jill's statement about pregnancy is actually spoken to her husband (to convince him to have "the talk" with Brad), and her "shocked reaction" is in response to Brad yelling at her and storming out of the room. Not that you'd know it, of course.
In another episode from a later season, Jill hires a professional (played by Tom Wopat) to install granite countertops, only to find that he's the same man who once flirted with her at the gym and tried to ask her out. Nothing happens between them, and Jill actually fires the guy because his behavior makes her so uncomfortable. The advertisement, on the other hand, shows the two of them kissing passionately (which actually happened during a Dream Sequence in a previous episode), Jill tearfully confessing "He kissed me!" (which he did — without her consent, right before she fired him), and Tim opening the front door and coming face to face with the flirtatious handyman (who actually just came back to get his tools).
House: Happens far too often. For example, the trailer for an episode during the Tritter arc had the following exchange:
House: This test isn't exactly FDA-approved.
Wilson: You committed a crime! Do something!
The reality, however, was more like this (somewhat paraphrased):
House: This test isn't exactly FDA-approved. [the test goes exactly as planned with no ill effects]
House: [much later] Hey, Wilson, Tritter is still bugging me about my drug habits, which, As You Know, I did some illegal stuff to support.
Also, the trailer for the season 5 ep. Lucky Thirteen made Thirteen's sex scene look way hotter than it was
Can't forget the various romances that also were teased to come to a culmination including House making out with Cameron in Season 3. She turned out to only be trying to distract him long enough to stab him with a needle to get a blood test
Another part of the trailer for this episode shows House saying he has brain cancer when later in the episode he reveals it was a con to get drugs implanted in his brain
The end of Season Five did this the most because all the revelatory stuff it showed such as House sexing up Cuddy was solved very quickly because it was all a narcotic induced hallucination
This trope has been so overdone for House, anytime you see House getting "some" in a trailer it would be safe to assume shenanigans.
The episode with the suicidal author. Turns out, he was just trying to prove that she was still suicidal to extend her psychiatric watch.
Author: You really think I believe you're going to help me commit suicide? House: I'm giving you a choice.
The ad for the sixth season showed Cuddy with House's voice saying that she had said yes, but he heard no which could be seen as that House had proposed to Cuddy and she had said yes. Turns out that he was talking to Wilson about how Cuddy had given him permission for an insane treatment on his patient and House was having second thoughts about it.
The original, pre-pilot trailers put a lot of emphasis on Robin, talking about how she changes everything in Ted's life, so on and so forth, making it blatantly obvious that she's the "mother" of the title. She's not.
Future Ted: And that kids, is how I met...your aunt Robin. Son: What!? I thought this was about how you met Mom! Future Ted: I told you, it's a long story!
Newer trailers in Germany feature only various scenes of Barney, letting it appear as if he were the main character.
Both American Season 7 recaps (one's for the Season 7 finale, the other's for the Season 8 premiere) are completely untrustworthy. What makes this really egregious is that these aren't trailers, but recaps. They're supposed to help you get caught up on the series, and they fail at doing this. They both show Robin telling Barney she might be pregnant, and if so, he's the father, but leave out the part that Robin's not pregnant, and is in fact infertile. Both recaps also leave out important cliffhangers that viewers are already supposed to be up to speed on. The Season 7 finale recap leaves out the cliffhanger befroe the finale that Lily's going into labor in NYC while Marshall is stuck in Atlantic City, stone drunk. The Season 8 premiere recap leaves out the finale's cliffhanger of Ted running off with his old flame, Victoria, on the same day she's getting married to somebody else.
The Word of God released a blog post later that made it appear to be a miscalculation by the marketing department of Nickelodeon, who either didn't realize that the episode didn't actually do anything they claimed, or They Just Didn't Care, and release the trailer like that to hype up the episode.
Inverted with a Word of God confirmation that the trailer for 'iOMG' isn't the same as the iSAFW debacle and something major does happen.
It happened again in the episode iGet Banned. In the trailer, it shows Carly spitting out a smoothie followed by T-Bo telling her she's banned from the Groovy Smoothie. This makes it look like Carly got banned for bad-mouthing his smoothies on the show. However, the scenes were played backwards, T-Bo banned Carly because she yelled at him, and she was spitting out a smoothie she tried to make herself after getting banned.
Juno Awards: During the hype blitz in the lead-up to the 2010 show, the trailers stated that Nickelback and Hedley would be giving performances. Neither of them did. Nickelback didn't even show up (though that may have been caused by the fog...), but Hedley did and even PRESENTED ONE OF THE AWARDS and TOOK PART IN THE FINAL PERFORMANCE (Wavin' Flag, FYI). However with almost all live awards shows, the Stock Legal Phrase "scheduled to appear" nearly always appears in promos; this covers the network in case a fan who staked their entire being on a performer being on an awards show can't sue them or the promoters.
Kamen Rider Decade: At the end of the last episode came a fifteen-second trailer for the Grand FinaleMovie. The trailer shows an Evil Twin of the main character, the sidekick (who closed out the series Brainwashed and Crazy) with his arm buried up to the elbow in The Rival's gut, the female lead trying to kill the hero with a sniper rifle, and more. In the actual film, none of this happened as depicted, though two concepts (the female lead opposing the hero and a tagalong character becoming a Rider) were merged together. Reportedly, the movie was going to be like that, but they were forced to basically abandon the entire plot and start over from scratch. The trailer scenes finally showed up in the Director's Cut...as part of a dream sequence the female lead has at the start of the movie.
The trailer for Kamen Rider Faiz made us believe that there world be a lead female Rider for the first time. It was very convincing.
Kings: The marketing ignored the heavy religious overtones and the fact that the story was based loosely on that of King David. NBC apparently was afraid that religious audiences would find fault with their retelling, and that secular viewers wouldn't want to watch a show with its basis in the Bible.
Law & Order: Special Victims Unit: A trailer for the newest season used a shot of Olivia looking surprised with a shot of Elliot and Dani about to kiss, adding up to sexual tension at its max. In the actual episode, Olivia never saw the kiss, which was just an accidental quickie after the two had a few drinks. The trailer made more fans squee than the episode.
SVU does this a lot, actually, putting small shots together in trailers or just taking them out of context and making them seem far more interesting than they actually are.
Another particularly bad SVU example: the trailer showed identical twin boys pressed against opposite sides of a wall, as the voiceover said "How can they tell which one committed the murder... when they have identical DNA?!" Not only was this not what the episode was about at all, not only was the aforementioned visual the last shot of the episode, not only was it that this spoiled the major twist of the episode (that the murder suspect's sister had been born a boy and raised as a girl after a botched circumcision), but it also spoiled the additional twist at the end of the episode (when the two collaborate to kill the doctor responsible). In fact, the question that the voiceover dramatically asks in the trailer is never even answered in the episode, and it's strongly suggested they'll go free.
Yet another notorious example was a trailer for an episode where Stabler went undercover and got shot by smugglers he was investigating. The trailer made it look as if Stabler was at death's door, with a shot of Benson pleading for him to survive. Not only did Stabler survive the shot in the actual episode, but he was out of the hospital and even helped nab the bad guys one commercial break later.
One trailer had Cragen tell Olivia that she was "Dismissed", making many people think that she was going to get fired. Instead, while Cragen was pretty pissed at her, he was basically saying "Get out of my sight"
The Australian network who show this (Network Ten) basically make all their SVU trailers into one of these two versions:
Elliot does something to a perp that he shouldn't out of anger and it could cost him his career.
Benson gets too emotionally involved in a case, does something she shouldn't, jeopardises the case and it could cost her badge.
One of the USA Network’s standard promo for the show has what appears to be Elliot casually asking Fin what his favorite form of torture is while the two are relaxing and playing cards. However this scene never appeared on the show. The clip of the card game is from the episode Class while the torture question was from Uncle and asked to a suspect Elliot was trying to get to confess.
This seems entirely in keeping with the UK version.
LOST: A preview for the episode "Stranger in a Strange Land" promised that three huge questions would be answered in it. These turned out to be the meaning of Jack's tattoos, what happened to the children the Others kidnapped and what happened to Cindy the flight attendant. Those last two have the same answer so many viewers argued they shouldn't count as separate questions, and it's not like many people were chomping at the bit about the first one either. The producers immediately said they never intended the episode to be one that was full of reveals like that, and blamed the network for unduly raising the viewers' hopes when it became one of the show's most unpopular episodes.
A preview for the episode "Outlaws" made it look like Sawyer was pointing a gun at Jack. The clips of Sawyer pointing the gun and the clips of Jack looking scared were actually taken from two entirely different scenes. Sawyer spent the entire episode hunting a freakin' boar.
Season six has done this. The trailers for the first five or six episodes mixed footage from all of them together, in a attempt to make a fairly slow moving and talky arc seem more exciting. Jack destroying the mirrors in the lighthouse was in pretty much every trailer despite not happening until episode five. The ad for "The Last Recruit" showed Sayid aiming a gun at Desmond and firing; in the episode, he doesn't fire it and Desmond's fate is left ambigious.
Trailers for "Dr. Linus" made it look like Ben was going to die in it. Ben not only survives, but makes it to the final episode alive.
Mad Men: The main character Don Draper changed identities with a dead guy during the Korean War and has been hiding it ever since. A promo for the season two episode "A Night to Remember" had Joan Holloway announcing, "Someone people think is dead is not dead," in a context intended to make it look like she was going to find out his secret and out him (or threaten to, or something). In fact, she'd spent the episode reading TV scripts for work and was talking about an upcoming storyline on a soap opera.
Series creator Matthew Weiner is notoriously closemouthed about upcoming episodes, and accordingly, the previews these days have become so impenetrably cryptic they have to be somewhat tongue-in-cheek, featuring very short, disconnected and completely unrevealing clips like people hanging up phones, putting on their coats and uttering only the most generic lines: "Get the door." "Where are you calling from?" "I'm sure you'll figure something out." The Internet has produced many parodies.
Masterchef: The commercials for the U.S. version of this show only featured Gordon Ramsey as the judge. They completely failed to mention that there's two other judges involved in this.
Medium: The Season 5 finale is being billed as the main character's "last vision". Which it is...on NBC. The show is moving to CBS next fall.
Promos for the first season finale showed Joe becoming panicked when he loses one of his daughters in a store. This turns out to be a dream...of Joe's oddly enough.
Merlin: The trailers for this NBC miniseries implied there was going to be a big huge battle between the title character and Queen Mab. In reality, while there was some shrieking, a few fireballs thrown, and other cool magical effects, the whole thing actually ended with everyone just turning their backs on her and forgetting her, refusing to believe in her. A very effective and creative way to defeat a villain, but it was probably rather disappointing for those who wanted to see Mab turned into a crispy critter.
Merlin: On the subject of this show, a trailer for one episode of the BBC series had Merlin dramatically reveal to the court that he was a wizard. In the actual episode, no one believed him and the scene had no impact on the plot.
The trailer for another episode made it look very, very much like Arthur was going to find out about Merlin's magic. And just before the episode started, the announcer said 'it had to happen eventually!'. Everyone got very excited about this. Turns out what Arthur saw was just ambiguous enough for him to believe Merlin hadn't done anything.
Mighty Morphin' Power Rangers: In the lead-up to the 3-parter "The Wedding," in which Lord Zedd and Rita Repulsa get married, Fox did a promo of the "Someone's getting married...who could it be?" variety, and seemed to suggest that it might be one of the Rangers, perhaps Billy, or even Tommy and Kimberly! Never mind the fact that they're all supposed to be teenagers...
In May 1995, the actors who play the Rangers out of character did a few rather ambiguous promos for a Fox Kids special entitled Talkin' It Out. From the way thepromos were put together, they seemed to suggest that the special was about the cast pushing the difference between reality and TV-programming fantasy for a good 30 minutesnote the special ran commercial-free, even preempting an episode of Carmen Sandiego. When it aired, however, it turned out that the Rangers were barely even in it, only appearing during a short introduction to briefly discuss what we were about to see, and suggest to younger viewers that they watch with their parents. The remaining 29 minutes involved John Walsh interviewing children about the then-recent Oklahoma City bombing and how it affected them.
Monk: A trailer for the seventh season finale. Narrator: "You'll never believe what he finds [at the site of his wife's murder]..." What did he find? Nothing. In fact, the episode was about him admitting that there wasn't anything to find. Though to be fair, no one believed it.
My Name Is Earl: Most trailers will always show footage from the flashback scenes, giving you the impression the show is just about an idiot doing stupid things.
This isn't really deceptive, the show got a lot of mileage out of pretending it didn't approve of Earl being a colossal jackass for Rule of Funny because he could fix it in the non-flashback part of the episode.
Nattens barn: The trailers for this Swedish 90s miniseries made it seem like a vampire/supernatural story, while it was in fact a perfectly realistic series about a Romantic Two-Girl Friendship between two Goths.
NCIS: This preview for the season six finale made it look like Ziva was going to kill Tony on her father's orders. Pretty shifty of CBS, but at least the episode itself was good.
Under Covers, which has a giveaway title as it is, was played out as being an actual hookup between Tony and Ziva. It's really too bad that the big reveal was five minutes in, and that it was a repeat.
The Office: NBC once promoted one episode as a Halloween show, with scenes of Dunder Mifflin in the spirit of the season. Turns out that any Halloween-related material was relegated to the Cold Open in the first few minutes of the show; it was a regular episode all along.
One Tree Hill: One promo for one episode outright stated that Peyton was going to once again have feelings for Nathan. Cue the episode where Nathan and Peyton become partners on a project and spend the rest of the episode having fun with no mention of romance at all.
OZ: The fourth season went on hiatus following the stunning death of Simon Adebisi at the hands of the formerly pacifistic Kareem Said. When the show returned, one of the promos featured Said shouting "Adebisi lives!" In the actual episode the line didn't signify that Adebisi was actually alive; Said said it after killing someone else as a statement that his years in prison had turned him into a violent murderer just like Adebisi. It was still a powerful scene, but the previews had viewers feeling ripped off anyway.
The Person of Interest episode "The Crossing" had a promo that was not necessarily untruthful, just misleading. The promos fully divulged the fact that one of their police contacts would be killed. The promo wasn't wrong, it just implied that the victim would be Fusco when instead it was Carter.
Pretty Little Liars: ABC Family's trailer of the season finale switched out which characters were in a car accident.
Red Dwarf: During the middle of its run, this show had an intro sequence that made it look more like some kind of high-adventure show than an irreverent comedy with a sci-fi backdrop.
The trailer for the sixth episode, "Sex and Drugs", suggested that the price to heal Nora's infection was Charlie's freedom, and Drexler would make her a sex slave—at least for one night. That was only the editing, though. While he was clearly attracted to her, when he said, "I want her," he did want her - to kill his neighbor who's been torching his opium poppy garden.
"Kashmir". Monroe's meeting with Miles exists only in Miles's mind.
Secret Girlfriend: The trailers implied that the show would primarily be about two pervy slacker guys trying to get women to perform activities of a sexual or suggestive nature, completely ignoring the fact that the viewer is experiencing the actual protagonist's experiences (kind of like Being John Malkovich) and is about the nameless protagonist's attempts to deal with a psycho near-ex-girlfriend who won't stay broken up, a cute girl he likes but wants to protect from the first woman, and the zany antics of his two best friends (the aforementioned slackers).
The Secret Life of the American Teenager: The episode previews are usually either uninformative or edit the footage together in a very misleading way. For example, there were numerous previews hinting that Amy and Ricky had feelings for each other or that they were going to get together long before they finally became a couple in season three.
Sherlock: Those infamous official Korean trailers that make it appear Sherlock and John's relationship is the focus of the series. Anyof them.
Showoffs: Promos for the 1975 ABC game show, which were taken from the pilot episode taped in May 1975, had to be severely edited because its intended host – Larry Blyden, a popular game show panelist of the early 1970s and who had just finished a stint as moderator of What's My Line? – was killed in a car accident while vacationing in Morocco. The intended promos featured Blyden on-camera congratulating a winning contestant. Bobby Van – a stage veteran and popular Goodson-Todman game show panelist – was quickly hired as host, and the hastily edited promote included his name.
The '60s, NBC's promos for the mini-series made it seem like Jeremy Sisto gets Julia Stiles pregnant when in actuality their two characters don't even know each other. Sisto actually plays one of Jordana Brewster's love interests.
Sleepy Hollow: Fox's trailers prior to the premiere strongly suggested that this would be a dark, brooding, action-packed supernatural horror series, through the use of dark camera shots and pounding background music. Now that the pilot has aired, it's clear that the "action-packed supernatural horror" part is entirely correct—but the trailers entirely failed to show that it's also funny. The Fish out of Temporal Water plotline is frequently played for laughs, there are plenty of witty one-liners in the dialogue, and the general tone of the show is more Grimm than it is grim.
The Sopranos: Tended to do this a lot, with the trailers playing up the mob violence that was rarely the center of the upcoming episode.
The trailer for the final episode on A&E promised "You won't believe how it ends!" In case you were one of the people who missed the controversy at the time, it didn't. The show just cut to black, leading many people to call their cable company and complain.
So You Think You Can Dance: One episode was promoted by Fox with a clip of Nigel Lythgoe shouting "Get off the stage!", suggesting that he was so angry at a contestant's performance he wanted them to leave. As shown in the actual episode, however, he was shouting out of enjoyment, and telling them to get off the stage because they'd made it to the next round.
One of the later episodes of the Australian version's first season was promoted with the audience booing and leaving the set, with the voiceover saying that someone would perform so badly that the audience would walk out. What actually happened was that the judges asked the audience to leave for a short amount of time (I can't remember why, I think it had something to do with the voting).
Stargate SG-1: A preview for one episode revolving around the team being trapped in an unpleasant version of a Lotus-Eater Machine, with the trailer using Carter's line "How do we know this is real?" as if it were a serious question and dramatic concern. In the actual episode, this is just the set-up for a final joke to cap off what's otherwise a particularly dark episode.
For several weeks there, the trailers for Stargate Atlantis alluded to replicator involvement. "Or is it a Replicator trap?" "Is he really back from the dead, or is it another Replicator?" Needless to say, Replicators weren't even mentioned in those episodes.
Stargate Universe follows the trend for a recent episode. Footage of the crew running down the hallway is accompanied by the usual urgent voice overs, as if they're running to avert some disaster. In the actual episode, it turns out it's just the crew working out during the opening montage.
Two particular examples for the original Stargate SG-1. One, where it was hyped up that a team member would end up dying and a clip of O'Neill falling to the ground wounded in battle was shown (it ended up being the doctor who died). The second was set up with Carter finding herself alone on a ship with only illusions to help her. The trailer made it look like she and O'Neill would end up kissing, but in the actual episode it was only a fantasy of hers that passed through her mind for a second- two at the most.
To be fair, in the first example, the episode itself actually implied that up until the last five minutes or so. So it wasn't just the creators of the ad, but the writers as well who intended the audience to be misled.
One Star Trek: Voyager episode trailer was particularly bad in this respect, being designed around the line "He violated me" in such a way as to make it sound very much as though Seven was going to be raped by a crew member; the trailer even featured a "Who did it?" sequence with flashes of various male crew members' faces. The actual episode, however, was just about an alien culture trapping her in a laboratory for study and stealing some of her nanoprobes. The plot does play at Does This Remind You of Anything?, with Borg nanoprobes replacing date rape, but it was still incredibly misleading.
Special shout-out to the trailer for "Virtuoso." Not only does it have zero footage from the episode it is advertising, but it has Chakotay essentially ordering the audience to enjoy themselves.
The already terrible episode "Resistance" had a trailer implying that Captain Janeway would dress slutty and even sell her body to protect the ship. in the episode it's a 30-second scene that's basically a Distracted by the Sexy moment. Even Kate Mulgrew and some of the crew called them out on it.
In regards to Voyager, a website designed to nitpick the show refers to this phenomenon as PAL, for Previews Always Lie. See here.
In a comparatively minor case, SPIKE's trademark preview for Voyager makes it out to be an action-packed, phasers-firing thrill ride. "Network for Men" and all that.
Voyager's action quotient is such that it's not entirely unwarranted. Now, when they tried to do the same with The Next Generation...
A trailer for some season 7 Voyager episode during its run that featured Kim saying "Ambassador Spock" in a shocked voice, leading me and many in the audience to tune in in hopes that everyone's favorite Vulcan would show up. As it turns out, Spock was mentioned briefly in one conversation and that 'shocked take' wasn't even in the episode.
Another trailer similarly name-dropped Captain Picard; the interview review The Cynic pithily remarked "dropping Picard's name will not get them Picard's ratings."
There's also the trailer for "Survival Instinct" which showed brief flashes of Borg-related stuff and culminated in Seven of Nine declaring "I will...return...to the Borg." In reality, two words were omitted from the line she actually said, which (omitted words emphasized) was, "I will not return them to the Borg." "Them" referred to three other ex-Borg whose still partially-Borgified brains suffered a major malfunction, and the only way for them to survive longer than a month was to let them be re-assimilated.
The trailer for "Tsunkatse" plays up a fight between Seven of Nine ("Voyager's Battle Babe") and an alien played by Dwayne "The Rock" Johnson. In the episode, that was treated as more-or-less a warm-up for the real climactic fight (which didn't involve a professional wrestler).
At least twice, a promo has used the voiced-over line "Has Voyager entered a parallel universe?" while showing the crew dealing with weird alternate versions of themselves. In one instance, they were actually dealing with scam artists posing as them, while another time the weird alternate versions were characters in a holo-novel.
The trailer for one Deep Space Nine episode showed the Enterprise being destroyed... or so we thought. Turns out it's a ship of the same class, called the Odyssey (Justified, maybe, in that Word of God says that the point of it happening in the episode was to tell the viewers "This might very well happen to the Enterprise" and to make them think of the familiar ship in that situation).
A trailer for Deep Space 9 on the CBS Reality channel showed how to do it when you've no idea which show you're talking about. It went on strangely in poetic terms, including the line "When the universe sleeps...Enterprise wakes (and basically saves us all)." Huh?
The trailer for the Star Trek: Enterprise episode "Cogenitor", about an alien species with 3 genders, made it look like a comedic sex romp by focusing solely on the brief comic relief moments in the episode, such as Phlox offering to show Trip photos of tri-gendered sex and Malcolm awkwardly flirting with an alien. In actuality, it's one of the darkest episodes in Trek history, raising complex questions about human rights and moral relativism, capped off with a deeply tragic ending.
The trailer for "Bounty" is based around the line "T'Pol's in heat, and she needs relief" while showing her behaving in a blatantly sexual manner. T'Pol does go through the Pon Farr in this episode (thanks to an alien pathogen), but that's the B-plot; the A-plot, and the reason the episode is called "Bounty," is Archer being captured by a Tellarite bounty hunter. (The Klingons put a price on Archer's head after he escaped from their gulag Rura Penthe several episodes earler.)
Final Star Trek spin-off example: UK TV channel Virgin 1 markets Star Trek: Enterprise on the basis of the handful of relatively sexy moments that make up the 4 seasons. While it might have featured more blatant sexual situations than the previous Star Trek series, the show was still pretty tame by most modern standards.
Supernatural: There's a trailer which makes it look like Dean set Jessica on fire.
And let's not forget the one that makes it look like the Crossroads Demon seduces Dean. And the episode summary even said that.
Previews for season nine made it looked like Bobby, who had died back in the seventh season, had mysteriously been resurrected and was aiding the boys again. As it turns out though, this wasn't the case: "Bobby" was actually just a figment of Sam's dying imagination and represented the part of him that felt it was his time to go.
Survivor: Has done this. Especially in Samoa, they tried to edit it so that people were thinking about eliminating Russell..except for some incredibly odd reason, seeing the episode brought out no talks about actually doing it.
One of the early seasons of Survivor featured an episode trailer that vaguely described some kind of horrific accident occurring, while flashing footage of crocodiles. An accident did actually occur (a contestant passed out due to smoke inhalation, was burned by their campfire, and had to be evacuated), but involved no attack by a wild animal of any kind.
That '70s Show: A commercial for one episode featured a scene where Donna told Eric she had to leave him. It turns out this scene was part of a dream sequence. Perhaps the shows only dream sequence played like a normal scene. Although they didn't get married, they remained a couple until Topher Grace left.
Top Gear: Plays with this, especially since season 3. Their previews are not only useless, but also mislead on what the episodes actually mean.
...Hammond falls on a valley...
Top Gear Season 16 had a preview which went, "Tonight! I wear a hat! Richard wears a hat! And James! Wears a hat!". And true to their word, they all did!
The reality series Total Divas had one scene that appeared in almost all of their commercials for season 2, a scene of Summer Rae slapping Natalya Neidhart across the face. The commercial made it appear as though Summer slapped Nattie because Nattie said Summer dresses like a stripper. In the actual episode, the slap occurs after Nattie insults Summer for being 30 and still single.
The Twilight Zone has an odd case, a sales pitch to the sponsors of the series, where Rod Serling outlines a few episodes from the first series. When talking about Escape Clause it splices in footage of a car being hit by a train, planes crashing and he talks about homicides. The actual episode has none of these things.
24: Cleverly done in the trailer for the 13th hour of Day 7. Scenes show the President being taken hostage, Jack fighting off a task force that's invaded the White House, a character (Bill) being caught in an explosion, and the results of said explosion leaving Jack falling to the ground and choking up. That's not the lie part: all that stuff happens. What sets this apart is it all occurs in the first ten minutes, rather than the entire episode as the trailer implies. Most of the episode is spent on Jack following a lead on who was collaborating with the White House attackers.
The Vampire Diaries: One season 4 episode was advertised as being the return of much-loved character Katherine. She only appeared as a hallucination. Though this ended up having its own payoff when Katherine appeared for real later in the season, with nothing in the previews to suggest it would happen.
Veronica Mars: The Australian promos described the show as "What would you do if your best friend was murdered, and YOU were accused of being the murderer, and the whole school hated you?", something that the main character was never accused of in the show.
Nickelodeon aired promos for "Crush Week" starring Justin Bieber and the girls from the cast of Victorious. One thing present there was a new episode of said show called "The Wood". The promos hinted the possibility of Tori and Beck becoming "more than friends" (read: a couple), showing a scene of her calling Beck on her phone, expressing love and offering to tickle his tummy. Almost immediately, fans of the Beck and Jade pairing that is currently present on the show raged and bashed the thought of said idea. Then, when the episode aired, it had next to nothing to do with love or pairings. It was a fusion of two clips-one with Tori calling her aunt about their puppy, another with Beck ordering a pizza. This made Jade think Tori was hitting on Beck, causing them to ensue hilarity. Thus, the Beck/Jade shippers got worked up for nothing.
Although at least that was what actually happened in the episode itself, with a reality show cutting those two conversations together in-universe, it wasn't created by the promo department.
The promos for "Jade Gets Crushed" make it seem like the premise of the episode is Jade going on a rampage. Really, she's significantly nicer in the episode than usual.
Aside from having scenes that never appeared in any episode, the trailer implies that Rick and Shane have a serious falling out while engaging a horde of walkers. They do, but not until much later in the season and in a completely different context and setting (the situation with Randall). The scene in the trailer is from a deleted sequence where they go to the Vatos retirement home and see that everyone's died and become a walker.
It implies that Shane and Andrea, and possibly Dale and T-Dog, separate from the group and go off on their own. This is discussed but never acted upon in the premiere, and it becomes a moot point because everyone moves to Hershel's farm.
The season 3 trailer has a shot of Rick and The Governor seemingly walking towards each other at the front gate of the prison, and Rick saying, "We took it... this is ours. We spilled blood for it." The shots of the characters are from two different episodes (The Governor walking towards the National Guard convoy in "Walk With Me" and Rick speaking with Oscar and Axel in "Killer Within"). The two characters never actually meet until very late in the season.
The season 4 trailer:
An early shot has Bob Stookey standing outside the Big Spot, then hearing screams from inside and going in. It's not the case in the final episode - he's simply standing outside and walks in when he knows the coast is clear. There's a walker attack, but it's actually caused by him when he tries to take a bottle of alcohol.
The trailer implies that the attack on the cellblock was caused by a saboteur, while in the episodes themselves, the group figures out that it's been caused by a virus almost immediately afterwards. A later scene has Glenn seemingly telling Maggie that they should abandon the rest of the group and go off on their own, but it's actually a scene where he's telling her to stay at the prison while he and the others go on a supply run in the premiere.
The season 5 trailer makes it look like Rick's group is reluctantly joining forces with the Terminus group to get to Washington, using footage of Bob pleading with them and dialogue from Rick seemingly threatening Gareth and saying he doesn't trust him. In the show, Bob is ignored, and Rick's dialogue is actually referring to Father Gabriel Stokes, an unrelated character. Neither group ever seriously considers the possibility of a team up, and the Termites are massacred in the premiere, with the few survivors dying only a couple episodes later.
War of the Worlds: A rather dated example: The original "On the next" trailer for the episode "Candle in the Night" showed the aliens desperately tracking a rogue device to stop it falling into the hands of the humans, asking, "Can the team use the aliens' own episode against them? A View to a kill, on the next episode of War of the Worlds!". Answer: No. Because they're not even looking for it: it's a Bottle Episode about the team organizing a surprise birthday party. The events of the trailer refer to a throwaway B-plot about the aliens trying to find a lost probe.
The West Wing: In the network promo for the Season 4 episode "Election Night," there is a shot of Democratic strategist Will Bailey standing outside the campaign office in a thunderous rainstorm, shouting "NOOO" to the high heavens. In the actual episode, he is in fact shouting "NOW" in an attempt, however serious, to predict (and possibly cause?) the torrential rain that begins seconds later, thus leading to depressed voter turnout and increasing the chances that his liberal candidate, who is dead, might actually win in conservative Orange County.
Wheel of Fortune: In October 2010, the show ran a trailer hinting at a $1,000,000 win a few days later. It showed a contestant hitting the Million-Dollar Wedge (which must be taken to the Bonus Round, where one of the Bonus Wheel's 24 envelopes is replaced with a $1,000,000). The contestant in the clip actually lost the Wedge to Bankrupt, and with it, the chance at getting her million.
Wildfire: On a sleazier note, a trailer for this less-than-stellar dramedy showed one character inviting another to a Two-Person Pool Party, with a clear implication of sex. Since this was on primetime TV before the Watershed, in the actual episode the line was immediately followed by a blunt refusal.
The World's Worst Drivers: Australian television always markets shows like this one as if they're comedies, when almost all take the form of overly tense When Animals Attack-style shows.
WWE Tough Enough: One trailer for this show featured some WWE Divas as guest stars, and showed one of them slapping Jeremiah with the implication that he'd done something untoward to deserve it. In truth, he was just drunk and being goofy, and asked to be slapped in a moment of euphoria.
Wizards of Waverly Place: The promo for "Alex Charms A Boy" makes it looks like Alex sadistically charms some random boy into falling in love with her. In the actual episode, the boy becomes her boyfriend the old fashioned way, and she only puts a charm on him to get him to paint her.