Funny enough, James Gunn didn’t originally plan on including Howard the Duck in Guardians of the Galaxy because the original post-credits scene was supposed to tease Avengers: Age of Ultron.
In case you’ve somehow forgotten about Howard the Duck’s surreal appearance in Guardians of the Galaxy, he was briefly spotted in a display case during the main movie as part of The Collector’s…well, collection.
Later in the post-credits scene when The Collector sat by his destroyed museum, Howard (voiced by Seth Green) sat nearby and criticized the eccentric entity for letting Cosmo the Spacedog lick his face.
When Captain America: The Winter Soldier “stole” that, Gunn and editor Frank Raskin noticed in their existing footage that Beneicio del Toro looked to the side at a box, thus providing a way to sneak Howard in and redeem the character a little bit for that movie of his that still occasionally haunts our dreams.