Cheat Mode: At the title screen, enter Up, Down, Left, Right, 1, Up, Down, Left, Right, 2. A notification will scroll past to confirm the code has been entered successfully.
Secret Mode: At the title screen, enter Up, Up, Down, Down, Left, Left, Right, Right. The secret passwords 0C78000B1, C183400C1, 137D500D1, 8D4560042 and some messages from the developers will scroll past.
Final Level: Enter 000010450 as password to fight against George Foreman.