I’m pretty sure that was Jagged Edge with Jeff Bridges. I had the same complaint with the ending.
Neill Blomkamp is the worst offender for me when it comes to recent(ish) sci-fi.
He makes awesome sci-fi films that are original, interesting enjoyable and really get you invested in the plotline. Until the final act where he chucks in trite predicable Hollywood ending and calls it a day.
District 9 was still a good film, but definitely did that. Elysium would have been a good film but the ending which was rubbish.
Chappy was so badly reviewed I have yet to watch it.
I thought Return of the King had a weak-ass ending, but after the ambling goulash of it combined with The Two Towers, the ending was no big surprise.
The Mind Reader (1933) – Warren William grifts until the cop-out ending.
Outcast (1937) – After Warren William is barely saved from a mob lynching, the mood turns cheerful and lighthearted, totally destroying the tension and drama that was so carefully built up.
Susana (1951) – Producer-imposed happy end taints this otherwise interesting Buñuel film about the impact of a disturbed girl’s behavior on a family.
Danger: Diabolik (1968) – Arguably one of the greatest comic book adaptations ever made leaves a sour aftertaste owing to its super-lame non-ending and awful music.
Malpertuis (1971) – Dying, Orson Welles passes his life’s work (search for master race) to nephew in agreeably strange and surreal Euro-flick that’s spoiled by the Caligari-like end.
Last Days of Man in Earth a.k.a. The Final Programme (1973) – Adaptation of Moorcock’s Jerry Cornelius stories was probably ahead of its time – and still may be – but the cheap joke ending remains a detriment.
Cowboy Be-Bop: The Movie (2001) – I recall this being pretty good leading up to the Spike vs. bad guy climax…and then it’s virtually all talk.
Vidocq (2001) – Great story has science-based detective going up against mirror-masked killer into clever murders, but throws it all away by introducing supernatural elements before the logic-deprived revelation of the killer’s identity.
Revengers Tragedy (2002) – One of director Alex Cox’s best and least-seen films is an adaptation of a Jacobean-era play with original language intact. I would assume the unsatisfyingly abrupt ending comes from the play.
Elephant (2003) – A non-ending concludes this well-made film which offers no insight into two Columbine-like killers.
Alita: Battle Angel (2019) – A heinous cheat ending that teases a sequel.
If anything, they missed out the good of the three endings. The books ended with the big battle ending. Then the Scouring of the shire (which was the brutal cost of war ending) claimed to have been filmed, and I did miss it being in the film, even though I was bored by the final ending (Frodo and all the elves are off over the sea).
The Martian (2015) - The book explains how difficult orbital rendezvous actually is, but in the movie a character can just eyeball it and jump out into space.
Being There (1979) - Firmly grounded in reality right up to the end - then the director plays a nasty trick on the audience with Peter Sellers walking on water. It is as though They Might be Giants (1971) ended with Moriarty actually emerging from the darkness.
2001 A Space Odyssey (1968) - The Star Child suddenly appears: Is it a reincarnation of the astronaut? A child of the astronaut? An actual alien? Who knows? At this point who cares? Just play loud dramatic music and stun the audience.
Fantastic Voyage (1966) - More of a plot hole, but WHY DIDN’T WHAT WAS LEFT OF THE DESTROYED PROTEUS SUBMARINE DE-MINITURIZE AT THE END? (The book handled it much better.)
I actually thought the very last shot of this movie was perfectly executed: Watney asks for questions, every hand in the room goes up, smash cut to credits.
Literally!
Similar to The Martian, the book of 2001 by Arthur C. Clarke explains what that whole sequence (and indeed a lot of the rest of the movie) is all about.
Yes, both of them. Neither one of them ruined the movie, but if they were going to going to end by breaking the fourth wall they should have done it better. The Holy Grail ending was just pointless, they may as well have gone to black. Blazing Saddles overdid it, I was tired of it before it was over.
OTOH, maybe that just goes to show it doesn’t matter that much how you end the movie. Tons of movie endings are trite and sappy but people still like the movie. Going out of the way to make a particularly bad ending just to be different may be a waste of time.
Not the very very end, which I liked, but Final Countdown (1980) was great, building up a scenario of nuclear-powered US Navy aircraft carrier based out of Pearl Harbor dropped from 1980 into Dec. 6, 1941, the crew first slowly realizing what they’re facing and then the officers deciding that as US naval officers their job is to defend the US against an attacking enemy whenever they are. That is, until the last few minutes of the movie when that scenario is thrown away: just before the aircraft from the US carrier are about to take on the Japanese air fleet before it can reach Pearl Harbor, the same time “storm” that sent the carrier to 1941 suddenly reappears and sends the carrier and its planes back to 1980. 
Except for the slightly-redeeming “twist” at the end of the movie, naval officer lost in 1941 turns out to have been the mysterious designer and builder of the carrier, who lived out the last 40 years in real time and applied his learned knowledge of the ship to design it, so then who designed it?!, most of the movie was pointless.
The original Invaders From Mars was a lot of fun, and suitably creepy for kids, with a pretty suspenseful final act. But even as a kid I felt extremely cheated by the “wake up right before the big explosion kills the characters - it was all just a dream” ending.
Hell In The Pacific
Lee Marvin, Toshiro Mifune
A little masterpiece, except for the final 10 seconds. The original ending, downbeat but appropriate and realistic, was replaced at the last minute with a lazy obviously tacked on cop-out.
Incendies (2010, Denis Villeneuve) gripped me in a way that no other film ever has. It’s about a young woman who must uncover her family’s history by traveling to an inhospitable country with a war-torn past. It feels so authentic – except for a decisive event at the end that makes sense allegorically but is very far-fetched medically.
Yes, thank you. Since the OP started this I have been struggling to come up with a movie to fit this, and you have nailed it. They were supposed to be drunk, but still, the end was obnoxious. The same result could have happened without it being a high school play performance.
Less “lazy cop out” and more “desperately out of money”. Read up on the making of the film sometime - the whole thing was an utterly miserable experience for the cast. I think they did pretty well with what they had. (The lack of funds also gave us the coconut gag, as they couldn’t afford actual horses.)
I’ve mentioned this elsewhere, but the weird and wonderful Ruben Brandt, Collector ends abruptly with the suggestion that it was all a dream (despite the film already having long dream and dream-in-a-dream sequences), which was a pity given how original the rest of the film was.
And then there’s Donnie Darko. I spent a lot of the film going “Man, the payoff to this that explains it all is going to be epic” and then “Gosh, we’re getting close to the end and they’re running out of time to explain it” and then “Fuck - they’re not really going to explain anything.”
On the DVD they actually had some bonus material explaining the whole dimension time loop or whatever you want to call it, but it only revealed just how ill-considered the McGuffin was. Probably just as well they didn’t put it into the film.
Escape Room
Came out a couple of years ago. Premise is like Cube where a group of strangers all get invited to attend a swanky sounding event but it turns out they are locked in and must find their own way out while battling the obstructions put in place by whoever is operating this sadistic game. It was a very fun movie until the end when the dramatic reveal went off the rails. They billed it up so there is a sequel but I don’t think after such an exhausting adventure that to conclude by telling the viewers to tune in for a round two was a good idea.
It’s neither. The end of the movie is comedy gold. Yes, it may have been because of a lack of money, but no other ending could have been funnier, and it was perfectly in place with the tone of the movie.
I don’t recall many people complaining when it first came out. I think that’s a recent phenomenon where people are so used to movies ending in a climactic fight scene that when the trope is subverted, they can’t deal with it. Even at the time, it was revolutionary and completely unexpected (and good comedy is all about the unexpected) and it has become more so over time.
I didn’t see it on first release, but at a midnight showing before the release of Life of Brian, and the ending was quite jarring and the gag was nowhere on par with those that preceded it. But most of the disappointment was simply that the movie was over and the fun had ended.
An earlier draft of the film had about half of it set in the modern era; this got pared down to the few scenes around the elderly academic and the ending.
I think it worked just fine but I understand why some people didn’t like it; I just wanted to clarify that “laziness” wasn’t remotely the reason for it. If anything, it was comedic ingenuity adapting to the circumstances (like the coconuts).