If you go through the bedrooms of the different X-men there are multiple humorous references to their comic past and character. Here are some examples:
Wolverines room has a Canadian flag that has a funny inscription from his former teammates at Alpha Flight.
Colossus room has an easel with a painting he was in the middle of making.
Storm has a playful personal letter from Forge. She also has gardening books.
There is a bug in the Xbox version where the comic book for Colossus is not present. Nabbing the comic would otherwise grant Colossus an additional 2 points to his Strike and Body.
At several points during the game when you are talking with veteran X-men you can get bonus flashback missions where they relate classic X-men tales. An example of one is where Beast tells Magma of the X-mens first encounter with Juggernaut as told in X-men #12. In the flashbacks the X-men have their old costumes and classic look (Beast has no fur, Iceman has a snowman appearance instead of hard ice, Cyclops and Jean have their 60's costumes, etc.).
The second Raven game not to be released for the PC, the first being Black Crypt.