Steve Rogers: Big man in a suit of armor. Take that away and what are you?
Tony Stark: A genius billionaire playboy philanthropist.
During the scene on the Helicarrier where Bruce Banner "Hulks out" and jumps at the F-35B hovering just outside, we see the F-35B fire its guns, one inside each of its intakes. The F-35B has only one gun, externally mounted to underside of the fuselage. It would be impossible to mount a gun inside an aircraft's intakes.
From a bird's-eye view, the layout of the helicarrier's bridge forms the S.H.I.E.L.D. Eagle logo.