Win water buggy race mini-game:
Intentionally lose the water buggy race mini-game, then immediately press
R + A + B when the screen fades to white. Your water buggy can go faster
during the next attempt.
Princess Corona:
Successfully complete the game under any difficulty setting. Return to the
title screen after the ending sequence. Load the previously completed
saved game to unlock Princess Corona.
Doraemon message:
Unplug all controllers and turn on the Nintendo 64. Doraemon will appear
and say a warning at the opening screen.