I remember discovering that if you let the demo screen progress to where your ship is captured, you can then control the new ship! You basically got 20-30s of free Galaga haha. The catch was the demo still tried to run, so it would yank you around some while you tried to play.
That one was fun but sometimes would crash the machine and it'd have to be power cycled to go back into service. The bug is still in the Galaga/Ms. Pac Man combo cabinet but it actually does reboot on its own instead of locking up the machine. Think that's also true for the 20-in-1 cabinet one of my friends owns.
