I still can’t stop but think how stretched out the Hobbit films were, for an otherwise short book. That’s a sin that stains forever with me. The Lord of the Rings films, do have their own flaws, but they’re fairly contained and can be debated as to whether they were good or not. I have so much trouble excusing anything with the Hobbit though.
And I hope we never, ever see anyone tackle The Silmarillion. Simply because, there will be so much improvised fluff in that would-be film, that it’d make the Hobbit films blush.
Lightyear (2022) had a trailer that is straight up false advertising. The trailer shows him contacting Star Command, something that never occurs in the movie. Still bitter about that.
Battle Los Angeles (2011) probably the biggest gap between the trailer’s quality and the film’s quality I’ve ever seen.
Giglie (2003), a movie on a lot of lists for being one of the worst of all time. The story behind it is that Ben Affleck and J-Lo got together during filming. The problem is, it wasn’t a romcom. J-Lo’s character was a lesbian. But because the of their real life romance, they rewrote the ending so the two get together.
Pretty crazy that happens six years after this scene from Chasing Amy (NSFW, gay slurs):
spoiler
https://www.youtube.com/watch?v=1EbSU5Zyx9Y
Edit: And someone made a docu titled Chasing Chasing Amy about how the movie treats gay issues: https://filmobsessive.com/film/new-releases/chasing-chasing-amy-allows-two-truth-to-coexist/
Edit: and you can watch it now: https://www.youtube.com/watch?v=wZTQbv1HUhg
I’ve noticed this a fair amount. It seems like deleted scenes or dialogue unattached to the footage gets used to build the trailer. Seems especially used for heavily CGI movies.