Alternate Stage 1 Music:
During stage one of either Arcade or iPhone Mode, pause the game and shake your device until you hear the chime sound. Do it in Arcade Mode and you unlock the alternate music "DoDonPachi Dai-ondo", do it in iPhone mode and you unlock the Remix.
Unlock Hibachi for iPhone Mode:
On the Ship Select for iPhone Mode, Hit B type once, then A, B, C, A, B, C, B, C, A, B, C, A, C, A, B, C, A, B. Hibachi will appear at the bottom of your screen to confirm the unlock of Hibachi. Or you can simply beat him In-Game and that will achieve the same effect.
Alternate Music Options:
Simply beat the game and The option to change the background music for both the iPhone and Arcade Modes will become available via the Sound Menu.
Access Open 2nd Loop:
If you want to enter the 2nd Loop of the game, you must collect at least 35 of the 45 hidden bee icons. They can be revealed by firing the laser so that the front edge of the beam (You can not simply drag the beam over the icon so that the side of the beam passes over it, that will not work.) and not continue. Defeat Shooty on Stage 5 and when Longhena asks you the question, select the top option. This will then take you to the 2nd Loop, which features Taisabachi as the Final Boss. An alternate way of achieveing the 2nd Loop is finishing the first loop and not dying at all.
Access Hidden 2nd Loop:
If you have collected all of the 45 bee icons and you are on the Ura Route when you defeat Shooty at the end of the 1st loop, selecting yes will take you to the Hidden 2nd Loop. This features Hibachi as a final boss appearing after Taisabachi has been defeated.