Well this game still has a few little surprises left for me. Just played a little today with my renegade, turian romancing engineer and noticed a little easter egg on the Citadel. If you go to the docking bay holding area and look at the memorial wall, there's a photo in the bottom left that feature an image of the early X05 pre-release
version of default Shepard and the words "John, call soon".
That's about as obscure as a video game self reference can get!