After you beat the song "Jumpin' Jack Flash" on Hard Rock mode, the game's final credits will roll. Thereafter, you'll be brought back to the game's title screen. Head to the Options menu, and then to the Gallery. Within, you'll see a small box on the bottom right corner with the letter J inside of it. Touch the J and the end credits will roll. You can do this any time you want to see the credits; and remember, you can touch the screen while the credits roll to get back to the previous screen.