When the SEGA logo appears, press the Reset button. Do this twice in a row for infinite lives. Your lives should now be displayed as two question marks instead of a number.
With the World Select code activated, when in-game, pause the game and press Up, A, Right, A, Down, A, Left. This will spin the casino slots for free items and other rewards.
At the Title Screen, before pressing Start but after the music starts but press Up, A, B, C, Right, A, B, C, Down, A, B, C, Left, A, and B. At the Options screen and a new World option will be shown.