The film -- starring Robert Downey Jr., Chris Evans, Scarlett Johansson, Chris Hemsworth, Jeremy Renner, Samuel L. Jackson and Mark Ruffalo -- hits theaters May 4, 2012
Director Joss Whedon walked Mark Ruffalo through a pivotal scene. The actor plays Bruce Banner/Hulk. "I'm excited to watch people see me Hulk out," Ruffalo tells Us.
Credit: Zade Rosenthal