In the world of film, an Easter egg is an intentional hidden message or character that is an homage to some other film, actor, or director. Sometimes the director hides the Easter egg in the film; other times it is surreptitiously placed by clever model makers or CGI artists. Either way, the Easter egg becomes a part of the film, and then it is up to eagle-eyed movie fans to find them when watching the film. Of course, most Easter eggs are discovered when watching digital versions of the film where scenes can be frozen or advanced frame by frame. One of the most charming and enduring Easter eggs is that of a famous robot.
Everyone knows that R2D2 (“R2” to his friends) is the cute, lovable robot who pals around with the nervous chatterbox droid, C-3PO, in the six-part Star Wars saga. But only a few sci-fi (especially Star Wars) aficionados know that R2 has appeared in several blockbusters spanning more than three decades. Outside of the realm of the Star Wars universe, R2 has a hard-working agent that has helped him appear in the following movies:
Star Trek (2009): R2 is seen flying through space, as part of a large cloud of debris
Transformers 2 (2009): R2 joins a number of flying parts to become the fully-formed body of Optimus Prime
The Goonies (1985): R2 makes an appearance on the deck of a ship
Raiders of the Lost Ark (1981): R2 is a hieroglyphic on a gold snake-wrapped staff
Close Encounter of the Third Kind (1977): R2 is standing on the bottom of the alien ship to the left of small exterior lights
For further reading: cracked.com/article_20356_5-recurring-movie-extras-you-wont-believe-you-never-noticed.html