Скачать или смотреть Cannon Dancer - Arcade - Unused Stage, how to access it and various glitches

The unused stage still exists in the game but cannot be accessed normally. To access it do the following:

Insert a credit, press start then hold the Test / Service Switch (default is F2 in MAME)

Keep holding Test and hold the following commands to access the unused areas:
P1 & P2 sticks right + P2 button 1
P1 & P2 sticks right + P2 button 2
P1 stick right + P2 button 2

In the lava floor area if you fall off the starting platform and use your i-frames to walk left you'll fall through the floor and land in the furnace area.

DO NOT attack the green electric enemies in the unused areas as this will crash the game.
There are loads of other command inputs you can use to access other parts of the game but these are the only secret / unused areas.
Be careful where you glitch too though as you can spawn into the terrain and won't be able to move. Other 'normal' areas can become a bit glitchy too but they're mostly OK.