I have a couple of examples ranging in extremes.
1. Avengers Infinity Wars shows the Hulk running at camera with ensemble of other heroes in Wakanda scene but while watching the movie, he barely made screen time.
- I think sometimes things like this make it to teaser trailers/trailers because they're put out early to build hype before a movie's release, eventually it comes down to editing and potential rewrites for various factors.
2. Downsizing (2017), holy crap this one was bad. Had to re-watch trailer just to make sure I wasn't misremembering and it was the official trailer. It comes off as a feel good fun movie, upbeat music, living like kings. When I finally watched it, absolutely different movie. Guy gets shrunk, his wife leaves him and takes all his money, he lives in squalor and develops a relationship with a gimped maid (not trying to be offensive, not sure how to phrase that properly) and ultimately gives up on the world by hiding in a bunker with a commune. Wow. Probably the most egregious false advertising ever.
I don't believe anyone should sue on these basis, its pointless and most people don't care, and what have you lost, a couple of hours and $20?