In the Nintendo 64 version of the game, two cheat codes can be activated on the pause menu that will each cause a picture of an unknown woman to appear in the top-right corner of the screen. Both pictures only get cleared from the screen upon returning to the main menu or changing levels, and inputting each code will cause one picture to overwrite the other:

•Holding L and pressing C-Left/C-Down/C-Right/C-Left/C-Down/C-Right will cause a monochrome picture of a blonde woman to appear.
•Holding L and pressing Down on the D-Pad/C-Left/C-Up will cause a color picture of a brunette woman to appear.