For me personally there are two:

1. Rocky IV: The scene at the end in which a bloody Rocky basically ends the Cold War with his "Can't we all just get along?" speech.

2. Independance Day: When the Americans find out how to destroy the alien ships and tell the british.

British soldier: "Sir, the americans are planning an offensive"

British officer: "Well, it's about bloody time"

As if every nation had just been sitting there with their thumb up their asses waiting for the US.