Actually, it wasn't a Marvel movie, thus explaining the lack of an Easter Egg or Stan Lee cameo. Movie rights to X-Men, Spider-Man, and Fantastic Four (I think that's it) belong to other studios. While that doesn't stop a Stan cameo (re: Spider-Man or, I believe, some earlier X-flicks), it does mean they're not tied in with the "Avengersverse" that the owned-by-Marvel movies have been setting up, so no Easter Egg to set up cross-movie continuity.