Is Marvel hiding a major reveal until the last possible moment?
By now, the post-credits scenes of Marvel Studios movies are events in and of themselves; one more reason to see each film as soon as possible to find out what final gags (or teases for future characters/storylines) will be revealed. The granddaddy of the trend, Nick Fury turning up after the end of Iron Man to reveal the very existence of the Marvel Cinematic Universe, was kept so secret that not even critics and preview audiences got to see it - and now that approach will apparently be revived for Guardians of The Galaxy.
While Guardians will have its official World Premiere tonight in Hollywood (and has already been shown to LA-area critics to an enthusiastic response;) neither the critics screenings nor the premiere have featured the film's final post-credits scene attached to the prints. According to director James Gunn, that's intentional: The final "secret scene" won't be shown to anyone until opening day, August 1.
Speculation has run rampant on social media since the early screenings began rolling out, but thus far no official/confirmed spoilers have managed to leak. Expectations and guesses have ranged from a teaser for Avengers: Age of Ultron to a scene that would explicitly connect the Guardians (whose film takes place in deep space) to the rest of the Earthbound Marvel Universe, while others have posited reveals for cosmically-connected Marvel characters rumored to be getting their own movies in the near future like Doctor Strange or Ms. Marvel.
Source: James Gunn