Game theory
What do you think would be the best strategy in the final duel?
I think, drawing first would be a bad move, because you would be able to only target one of the two opponents, and the other opponent would be able to eliminate you easily.
My estimation for the best move is to wait for an opponent to draw first, and then target that opponent, before eliminating the other opponent.
If the first drawer is targeting you, the best you can do in that case is to defend yourself.
If the other opponent is then also targeting you, you are all out of luck: Game over.
If the other opponent is targeting the first drawer, however, your chances for defense have improved somewhat. The first drawer has still the first mover advantage on you, of course.
If the first drawer is targeting the other opponent, he might succeed eliminating him, so you have basically a home run at that point by eliminating him.
All of this is moot, of course, if you know that only one opponent has a loaded weapon. In that case you should draw first, eliminating the only opponent that is a real threat.
So who was drawing first in the movie? I think it was Angel Eyes, but I'm not sure. If it was Angel Eyes, Blondie seems to be a bad player...