Sonic 1 Prototype - Illegal Instruction Error

NOTE: This error can be triggered on the PROTOTYPE version of Sonic 1 ONLY.
However, once you reach the end of Labyrinth Zone Act 1/2 on the final release, use a Spin Attack just as you finish. Then press down on the D-Pad.

This is a rather cool error - but it's more of a crash. There's 3 ways to trigger it:
(1) Sound Select (shown in video)
This works with PROTOTYPE Sonic ONLY.
1. At the title screen, press the following keys:
UP
DOWN
LEFT
RIGHT
A*
START
*Hold this button while you press the next one.
2. Go to Sound Select and change it to "92".
3. Press START and enjoy!
(2) Labyrinth Zone
Once you reach the end of Labyrinth Zone Act 1/2, use a Spin Attack just as you finish. Then press down on the D-Pad.
(3) This crash can happen when something happens that the game can't handle.