Instantly finish bike missions
During the mission, just before you acquire a King Chim Chim, hit [Select] to bring up the map. Press [Circle] to exit the map and snag the King immediately after the map disappears. If you do this correctly, when you get the King Chim Chim, you will instantly acquire all three of the necessary Kings and finish the mission. You can make the glitch easier to accomplish by pressing [X] right after [Circle], but doing so may bring up the Mission Info text box. Press [Circle] to clear it before returning to town, or you will be forced to reset the game.
View Vol. 1 and 2 Trailers Without Savegame Conversion
On the main desktop screen, hold [R1]+[R2] and push [Square], [Triangle], [Square], [Triangle]. Release [R1]+[R2], hold [L1]+[L2] and push [Right], [Up], [Right], [Up]. Release [L1]+[L2] and press [L3]+[R3]. If you do this quickly, a message will appear saying "Code input complete! The movie, "Vol 1 & 2 Preview" is added." You can view the movie on the desktop's movie player.
If you converted a save game from Vol. 1: Rebirth when you started a new game, the code won't work because you already have the preview trailer.