The scene where Loki stabs Agent Coulson exists in two versions. The original version shows the weapon piercing Coulson's body, the cut version does not. In various territories (Germany, Switzerland, Russia, United Kingdom and Ireland), the cut scene was used for the DVD release (why this was done i.e. for the German release is unknown, since it would not have changed the rating).
The brief non-dialogue scene that follows the closing credits was only included in later US showings of the film, having actually not been shot until after the film's US premiere. International DVD/Blu-ray versions include the scene.
The version of the film shows in AMC Theaters as part of a Avengers Marvel Phase One marathon features an exclusive intro from Agent Coulson, talking about the film and the character. These Coulson intros were later includes as bonuses in the Avengers Phase One box set.