Hidden Tower of Druaga
In the Museum hold L1 R1 and press Up Right Down Left Left Left. A pickaxe icon will appear if done correctly. Now enter the Tower of Druaga exhibit halls. Go directly forward until you run into a wall. PacMan will indicate that there's something there. Press X and he'll dig through the wall. You'll see a 3D battle between Gil and Druaga and a new Tower of Druaga to play.
Pole Position II
Go to the Test menu choose Dip Switches. Put Dip Switch 1 on and then return to the Main Game. Reaccess the menu and you'll see a new option called "Course".