One hit knock outs:
     Hold L + R and press A, X, X, A at the main menu.

High speed mode:
     Hold L + R and press X, X, Y, Y at the main menu.

Chicken heads:
     Hold L + R and press A, X, X, B at the main menu.

Toy block cars:
     Hold L + R press X, X, Y, B at the main menu.

Disable HUD:
     Hold L + R and press A, B, Y, X at the main menu.

Japanese Crash:
     Hold L + R and press B, X, B, X at the main menu.