Sound Test and Codes
You must beat special stage time attacks in under 4 minutes to unlock the Sound Test.
Hidden artwork 1: PGM 12, DA 11
Hidden artwork 2: PGM 12, DA 2
Hidden artwork 3: PGM 03, DA 0
Hidden artwork 4: PGM 04, DA 2
Hidden artwork 5: PGM 11, DA 0
Secret special stage: PGM 07, DA 07
I'm Outta Here!
Let Sonic stand still unattended for most of three minutes and he'll say "I'm outta here!" before jumping off the screen, at which point your game ends.