[Spiwak]

Wow, too many to count.

Orson Welles' Mr Arkadin (or Confidential Report) is, I think, one of the better examples of a movie gone horribly wrong in the editing room. The producers took it out of Welles' hands and cut it themselves. Criterion tried to make a final cut of it using footage from all the available cuts of the movie and Orson's notes, but even then I believe it's not exactly right. Also, Kingdom of Heaven is a good example of a director's cut that was actually seriously worth a double dip. Eyes Wide Shut also had that dumb digital censorship of naked bodies to make an R-rating...honestly, who the fuck has the right to tell Kubrick what to do?

As for movies that didn't happen that should have, the ultimate example has to be Kubrick's Napoleon. You can find the screenplay online if you're lucky (I don't remember where I found it), and it's hard to say but judging by the screenplay alone I feel pretty sure it would have been a classic. Sepaking of which, A.I. isn't a bad example, either. Sure, it was always meant to be Spielberg's project, but I don't think he would have completely fucked the ending like he did if Kubrick was alive to produce (or better yet, direct). Don't know much about Aryan Papers.