To access the bonus level, enter the password J5-B7-FB-84.
Top Cat has nothing on you when you're armed with this set of passwords.
Password Completed Levels
6B-88-40-H4 Megakat City
2H-02-72-H8 Megakat City and Bank
C9-7F-72-13 Megakat City, Bank, and Madkat Amusement Park
B4-89-B2-1H Megakat City, bank, Madkat, and Sea Boat