The movie that I saw that was most completely misrepresented was Arachnophobia. One trailer seemed to be composed entirely of John Goodman appearances, and gave the impression that this was a John Goodman comedy. In reality, he’s only in a very few scenes, and most of the movie has nothing to do with him. You could actually cut out his scenes and still have a coherent story.
All of the promotions for 12 Monkeys made it look like an idiotic film school project by a student who wasn’t very good at it. But it’s actually the best time-travel movie I’ve ever seen.
I saw it once when it hit the theaters and I don’t even remember that Goodman was in it, though I do remember that it was an extraordinarily dark film for something Spielberg was involved in.
Did it at least have some gratuitous nudity like Emanuelle?
He played the “comic relief” exterminator. He was often buried in a yellow jumpsuit, face mask, and helmet, so you could have not realized it was him.
Not that I remember. 
And not even the luscious Sylvia Kristel could hold my interest during Emanuelle.
The movie Admission looks to be a Tina Fey/Paul Rudd Rom-com. I mean, just look at the poster: https://upload.wikimedia.org/wikipedia/en/f/fa/Admission_movie_poster.jpg
Really it’s a movie about Tina Fey dealing with a son she gave up for adoption.
The version i saw was very dark. And i’d have to watch the original version to compare and I don’t want to put myself through that again.
Event Horizon. I expected a Sci-Fi adventure. I got a portal to hell.
I went to a weekend matinee showing when Jurassic Park first came out, and when the first scary dinosaur ate the first screaming victim, it seemed like a good portion of the theater was screaming children and parents hurriedly leaving. I’m thinking they were expecting more of a “Barney” dinosaur movie.
If you’re taking kids to a movie, wouldn’t Even Minimal Parenting mean you watch a trailer or read a review or at least tell someone you’re going, so they can talk you out of it?
I have a co-worker who, back in the day, took her (very young) daughter to the first Tim Burton Batman movie, fully expecting it to be an Adam West/Burt Ward campiness-fest.
ETA: My example is also back in the day, a gang of us high school guys going to a Rolling Stones movie. It was Sympathy For The Devil… Two hours of nothing but shots of the band in the studio recording that one song. Every tedious moment, 200 takes of the doot-doots… We walked out.
Robin Williams did a few such movies, where the first half was a side-splittingly funny comedy, and the second half was a drama, usually with a dark ending. In addition to Dead Poets Society, I think Good Morning Vietnam and Patch Adams fit this mold. As I recall, the trailers for those also showed the funny parts, and left out the sad drama.
Watership Down was another notorious one. If you saw the original movie poster you would at least have an inkling of what you were in for. But a lot of people apparently just assumed that it would be a fairly family-friendly animated film about bunnies. The DVD cover by contrast is not particularly enlightening and I could of sworn I saw similar images being advertised when the film came out.
Breaking the Waves Expected sweet love story about overcoming tragedy. Got bizarre sex fetish that ended in death.
…the Movie Angel Eyes, starring Jennifer Lopez and Jesus. (AKA Reese)
Here’s the trailer:
Looks pretty dramatic right?And the logline:
“While pursuing a suspect one night, Chicago Police officer Sharon Pogue (Jennifer Lopez) nearly becomes the victim of a fatal ambush until a mysterious stranger, Catch (Jim Caviezel), intervenes, disarms the assassin and saves Sharon’s life. A concerned citizen who just happened to pass by at the right time?”
What the movie actually is? A beautiful, mournful but touching romantic drama about two very broken people and how they come together. I love this movie. I never would have seen it though based on the trailer, I just happened to stumble across it late one night.
I know it’s significantly more lowbrow than many of the movies listed by others but Scott Pilgrim vs The World caught me completely off guard.
I had never heard of Scott Pilgrim and I was sitting around bored one night so I decided to rent the movie on a whim. I spent the first 15-20min scratching my head trying to figure out where the movie was trying to go and then this Indian guy dressed like a pirate came crashing through the roof and challenged Scott to a video game fight…and I didn’t stop laughing until the credits rolled.
Luckily I had no expectations for this movie. If anyone hasn’t seen it I’d think they should expect regretting it if they do.
One of the earliest of this ilk that stuck in my mind was a Goldie Hawn flick, Sugarland Express. Just mentioning Goldie Hawn immediately conjured up delightful wacky lightweight comedy, sweet silly fun. Uh uh.
…should have been that it was a movie by John Waters but what could be more innocuous than a movie called ‘Pink Flamingos’?
Same with *Jack. * Trailer: Robin Williams being silly playing a 10 year old. Actual movie: 10 year old coming to grips with the fact that he’s probably going to die in another 10 years.