The 10 Movies With the Most Abrupt Endings That Aren't Cliffhangers According to Collider

"Common wisdom will likely tell a filmmaker that they should take their time ending a story. A great way to make sure an ending is satisfying is to ensure it concludes everything that came before, and help viewers feel like they didn't waste time watching. Ending a movie's story too abruptly can run the risk of feeling random and being funny, which might be okay if you're making a comedy, but that's not exactly desirable if that humor wasn't intentional. There are abrupt endings to serious movies that actually work, however, and also aren't intended to be cliffhangers for future sequels to resolve. They'll often be there to make some kind of thematic point, or otherwise intended to impact the viewer in some way and leave them thinking. Some remarkable movies all used intentionally sudden endings for dramatic effect, and were mostly successful in doing so, even if these endings are sometimes frustrating on a first watch." - collider.com