Star Wars: Rogue Squadron - Rogue Leader
A very unique and unusual cameo. It's a picture, of an arcade unit, in a game. Once you beat all the regular one-player missions (or use the ?INSIDER passcode), you can view a Documentary, essentially a movie about the game's production which was filmed inside the designer's office. In that office, the designers have several arcade machines, including one of Donkey Kong. There is even a brief close-up of the machine's side art, with Mario, DK, and Pauline. Cool, if not strange. Thanks to TMK for the information.