The Avengers' Cobie Smulders, who plays S.H.I.E.L.D. agent Maria Hill, hit Letterman last night to debut a new clip from the much-anticipated superhero team-up flick.
The clip reveals some tension in the chain of command between Hill and Samuel L. Jackson's Nick Fury, and teases us with some important prototype tech being stored at S.H.I.E.L.D. HQ.
The Aveng