Steve Rogers: Big man in a suit of armor. Take that away and what are you?
Tony Stark: A genius billionaire playboy philanthropist.
When Tony goes after the nuke, there is a huge cut visible next to his right eye. This cut vanishes after the Chitauri ship is destroyed.
From a bird's-eye view, the layout of the helicarrier's bridge forms the S.H.I.E.L.D. Eagle logo.