Not sure if it has been mentioned on AP, but a hidden animation from the Indiana Jones pinball has been discovered after 18 years - Michigan J "dancing" Frog.

You can activate the hidden animation with this method:

1. Start the game with both flipper buttons pressed.

2. Get to the mine cart video mode and start as normal.

3. Count the right hand gates...Crash through the fourth right side gate.

wow, do you have to do all this while standing on one leg and holding your left nut while rubbing your tummy and scratching your head on a Tuesday afternoon?
why do they make these hidden displays so hard?