With the less than subtle franchise crossover appearances between the Marvel films all leading up to The Avengers, Joe Johnston has made it clear that any easter eggs or mentions of other Marvel properties in Captain America will be very subtle. Comicbook Movie says: There are links between all the Marvel films, mostly ones that only the fans will pick up on. We have several subtle references to certain elements in Thor, but since Captain America is a period picture taking place in the 40′s, there are fewer opportunities for contemporary links to the rest of the Marvel universe.
Original post:
Johnston says Marvel References in Captain America will be Subtle