In Episode 7, Scenes 1, 2, and 3, you can go ahead of younger Black Jack, but not too far. You can beat him to where he needs to go (listen to Luke to tell you when you need to turn).
Collect a power-up, then leave that place and return. The power-up will still be there and may be collected again. The maximum number of nitros that may be collected is five.
Finish the game, then save it to a memory card. Load the game from the options/memory card screen to chose any episode and scene. Choose quit to the main menu and save the game again at the options/memory card screen.
When being chased by the police, you can cut them off by hitting them on the back when they try to cut you off
While Luke is hanging out of the window drive slower, or he will go back inside the car. If you hit anything he will go back inside.