Rescue all civilians except for the second person on level 4.
Clear the game to enter the bonus room at the end.
A Rogan Costume and Infinite Credits will be in the room.
Get the Bruno costume when a maid comes out of a secret room, hands it to you, and wishes you good luck.
Now increase the credits past nine until "Free Play" appears in the options screen.
The costume will appear in the trunk of the car in the next time you play original mode.