After Orson Welles completed work on The Magnificent Ambersons he went to Brazil to work on a film called "It's All True" Whilst there, the film company behind Magnificent Ambersons butchered it with the result that what is now seen is incomplete. They also withdrew the finance for It's All True with the result that the film was never completed. However one of the stories in it called "Four Men on a raft" was allowed to be completed.
It's part documentary and here it is: