Jacob's Ladder
This is one of the best movies I have ever seen and probably one I'll consider a favorite. It's excellent. You will have a crazy array of emotions during this one.
Jacob's Ladder is clearly very much up for interpretation but my belief is that he is in purgatory the entire time the hallucinations/(and/or flashbacks) and realizations are happening. He's conquering his 'demons' to make it to 'heaven'.
This is a movie that should never be messed with or changed. I'm annoyed to see a low-rated remake was done a few years ago. I refuse to watch it.