When Captain America walks onto the bridge of the ship, he gives Nick Fury a ten dollar bill. Is this because he is amazed by the ship or is it some reference to the fact that he is from a time when African Americans weren't quite treated as equals yet?
Earlier, when Nick Fury meets Captain America at the gym, they have the following conversation.
NICK FURY: He's called Loki. He's not from around here. There's a lot we'll have to bring you up to speed on if you're in. The world has gotten even stranger than you already know.
STEVE: At this point, I doubt anything would surprise me.
NICK FURY: Ten bucks says you're wrong.
Source: The Avengers transcript on The Internet Movie Script Database
It turns out a camouflaged flying Helicarrier was enough to make Cap pay up.
Captain America pays Nick fury $10 in response to the bet he made with him in the gym about not likely going to be amazed by anything else he was shown.
Nick Fury bet Captain America that things would get stranger. Cap responded that things could not get stranger and boy was he wrong.