Unlock All Cars

At Password Screen
Password ...... Effect
47GIV3MECARS .. All Cars

Unlock All missions

At Password Screen
Password ...... Effect
IMFEDUPWITHTHIS Unlock All Missions

Unlock Sceptre and Mini-Rockets

Go to the cheat code menu within the game.
Password ...... Effect
10E6CUSTOMER .. Unlock Sceptre and Mini-Rockets

Unlock Vulcan and Flamethrower

Go into the options menu at the title screen and find cheats. Then type in this code
Password ...... Effect
5FINGERDISCOUNT Unlock Vulcan and Flamethrower