Debug Mode
To enter Debug Mode, play these sounds from the level select screen: 1, 9, 9, 2, 1, 1, 2, 4. Press Start and hold A. To start debugging, press B, then you can select any sprite in that level and put it on the screen. To select a different sprite, press A, and to place it on the screen, press C. Note that sprite selection is different from Zone to Zone. Also, instead of displaying the time elapsed, it displays the number of sprites currently on the screen.

Level Select
From the main screen, select Options. Select Sound Select and play sounds 19, 65, 9, 17, then push C. Press Start to return to the main screen, and when Sonic and Tails appear, hold A and press Start.