Re: Easter eggs?
All the talk about the mysterious "Phase Two" is a reference to Kevin Feige's classification of the films. "Iron Man" through "Marvel's The Avengers" was the "Marvel Cinematic Universe Phase One". "Iron Man 3" presumably through "Marvel's The Avengers 2" will be the "Marvel Cinematic Universe: Phase Two".
A little bit of teaser work there throughout the film.
Iron Man Captain America Thor Hulk
Black Widow Hawkeye Quicksilver Scarlet Witch Vision
Avengers: Age of Ultron
Superman Batman Wonder Woman
Batman v. Superman: Dawn of Justice