"Easter egg is an intentional hidden message, in-joke or feature in an object such as a movie, book, CD, DVD, computer program, web page or video game. "
like sex with the green woman in the movie.... stuff that you think you're the only one to notice....
lots of movies have easter eggs... usually the scene after the credits is considered an easter egg..
another example is in Iron Man... when that black dude looked at the silver unpainted suit and said "next time baby".. was an easter egg to the rise of ironmans sidekick.
the green chick in the movie was not an easter egg, nor was the iron man thing you're talking about.