Many of those references are pretty apparent: Tony makes use of Captain America’s shield to build a 
reactor, there are news reviews depicting the campus battle from The Unimaginable Hulk, and the put up-credit scene entails Agent Coulson discovering 
Thor’s hammer in a crater. Coulson will get on his phone with Nick Fury (we assume) and 
says "Sir, we discovered it," before the camera cuts to 
the center of the crater where Thor’s hammer Mjolnir is lodged.