Complete the final stage "Sacred Ground" to unlock Time Attack mode. This mode allows you to select five of the six weapons and the number of health that you want. After that you can play the extra stage again.
On the Plantation level, head to the "Rest Area" and go to the bottom where the water is located. Move left through the opening in the wall to reach the "Inner Wall" outside area. Booster 2.0 is required for this location. Continue until you find a door at the bottom left with a wall between it. Go under the wall and boost up until you reach the door. Use it to enter a "Secret Grave" with a big "Prinny" statue at the center. Examine the sparkling object to get the "Prinny Cap".
Unlock alternate music and character pointers at the title screen by completing Sanctuary Time Attack mode under the corresponding time limits:
MUSIC/POINTER - TIME LIMIT Running Hell music and Curly pointer - 6 minutes. Safety music and Sue pointer - 3 minutes. Toroko's Theme music and Toroko pointer - 5 minutes. White music and King pointer - 4 minutes.
Unlock the following bonuses by performing the corresponding tasks:
BONUS - HOW TO UNLOCK Boss Attack mode - Earn the "Best" ending. Curly Story - Obtain Curly's Panties and save the game. Nemesis challenge stage - Obtain the Nemesis and save the game. Sanctuary Time Attack mode - Earn the "Best" ending. Wind Fortress stage - Earn the "Best" ending.