Get at least 14 of the hi-scores to unlock a sound test option under the pause menu. Alternatively, collect at least 70 gold stars.
Collect at least 9 gold clocks to unlock the music player at the stage entrance screen. Alternatively, collect at least 70 gold stars.
Collect at least 70 gold stars to unlock the movie player at the stage entrance screen.
Reach the Pier Pressure bonus round (after Year Of The Pac) and get a score of 50,000 or more. If done correctly, a message at the results screen will confirm that a new map has been unlocked. Save the game, quit, then select the "Multiplayer" option on the main menu to find the new bonus map.