Furasshu-sama car
Quickly press Up(2), Down(2), Left, Right, Left, Right, Square, X at the car selection screen.
300 mph Car
At the car selection screen, press Circle, Square, L1, R2, Right, Left, Up.
Unlock C12
Beat a championship race with a class C drift car (i.e., Pickster) to unlock the C12.
Monster Eyes at LA Long
Take the shortcut on LA Long. As soon as you go on the river, turn around and go to the pipes. Inside the first pipe are monster eyes.