Continuity mistake: At one point near the beginning of the infiltration of the helicarriers, Captain America's chinstrap has a twist from his right jaw down to where it covers his chin. This is visible in two shots. The next time his right side is shown afterward, the twist is gone. The chinstrap is too tight for it to have flipped on its own accidentally, and the pad which covers his chin is molded so it wouldn't have sat properly on his face even if it had somehow flipped around. There were undoubtedly several prop helmets made, and this one must have been put together incorrectly.
Phixius
13th Apr 2014