The opening scene to this movie (crashed chopper in Vietnam)is a direct rip-off, ie exactly the same piece of footage as the scene in the Alan Parker film 'Birdy' where the chopper rescuing Birdy crashes. I only noticed this as I have recently acquired a heap of movies and am going through them alphabetically.
...but the crashed chopper scene isn't in these movies. (though I wouldn't have put it past Mel Brooks to include it in Blazing Saddles!) So how is your comment relevant? Out of the movies you mentioned I have Blade, Blade Runner and Blazing Saddles. You didn't mention Birth, Black Sheep or Black Snake Moan. It wasn't in these movies either.
It's funny you raised this because yes, the opening scene leads you to believe Nick was injured in a chopper crash.
But later in the movie when telling Billy how he became blind we find out that he was injured in a mortar attack and the chopper doesn't appear to come into it.
I've always loved this film, but it does feature some weird editing. EG One of the other threads discusses the unknown fate of Macready...the chief villain of the piece.
I get the window seat! You don't need it, you're blind!