We already know about the revealing post-end-credits scenes in the Iron Man and The Incredible films that tie these two properties of the Marvel Universe together (Spoilers: see Iron Man and Incredible Hulk scenes).
Now it’s been discovered that the two films also include nods to another Marvel property — Captain America.
/Film points out a blue serum in one of the latest photos from The Incredible Hulk, which is supposed to be the serum used to turn Steve Rogers into the super-soldier Captain America. I remembered something being brought up about this at the panel for The Incredible Hulk at the New York Comic Con last month. So, I went through my notes and sure enough, producer Kevin Feige confirms to the crowd, which had just been shown footage of the film, that the serum is a Captain America reference.
“Did you guys see the color of the serum? It’s Captain America’s color. So there you go.”
Holding the blue serum in the photo is Tim Nelson Blake as Samuel Sterns in human form. In the comics, Sterns is a janitor at the lab where Dr. Banner works, which is where he too is exposed to gamma radiation and becomes the Hulk’s nemesis, The Leader.
On the unconfirmed side, FirstShowing cleverly spotted a scene in Iron Man about an hour and 30 minutes into the film in which we see what looks like Captain America’s red, white, and blue shield in the background of Tony Stark’s workshop. (See photo below from FS, the shield’s at bottom left.)

In the comics, Tony Stark does not create the iconic shield, but he does make modifications to it for Captain America at one point.
Marvel announced last week the release date for First Avenger: Captain America (working title) as May 6, 2011, as well as a second Avengers movie due in July 2011.
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