Nothing can match the crushing disappointment of when a movie seems to be so perfect and then suddenly goes off a cliff. You know that what was good in the movie will almost definitely never be recreated with a better ending the seemingly limitless potential is wasted forever. Here are the movies that have most profoundly given me that feeling. (Insert obvious spoiler warning)
5. Reservoir Dogs
Reservoir Dogs was the debut feature film of the now acclaimed director Quentin Tarantino, following a group of criminals attempting to find the mole in their gang following a bungled heist. It has some of the best dialogue ever committed to the big screen and one particularly excellent scene with Michael Madsen and a cop tied to a chair. Almost the whole movie takes place inside one warehouse but its thoroughly engrossing and for almost its full running time its pretty much perfect.
The Problem? The last few seconds. That really is all that ruined this movie for me. A few seconds. In those few seconds four of the five surviving gang members (including the undercover police officer) are killed and the one survivor is arrested. The thing is the gang are never really seen as a bunch of ruthless bastards that you want to see punished not all of them, at least. The three most sympathetic members of the gang are the last three surviving killing two off and arresting one in the final few seconds made the whole movie seem like a waste of time. Killing off protagonists is an interesting ending that can work, but somebody has to be left even if its a villain. In Reservoir Dogs every major player is gone and its not even played out like a tragedy, it just kind of happens.