Press Left, Right, Down, A, and hold Start when Sonic appears from the hole during the opening sequence. Keep holding Start until game play begins.
Press Up(2), Down(2), Left, Right, Left, Right at the title screen.
View any level:
Press Up, Down, Left, Right, then hold A and press Start at the start screen.
Reach the end of any level with less than fifty rings. Enter the turnstile, then stop and jump directly upward. If timed correctly, the turnstile will stop spinning while it is off-screen. An extra life will appear when Sonic lands back over the turnstile.