Apologies if this has been noted already here, but I've run into the same bug twice now where I get three balls locked for multiball but the game doesn't register the third lock and starts going into ball search mode. I found out the hard way the first time that the game eventually drops all three balls - had wife holding the glass while I reached for the ball and they all came tumbling out -- nice way to end my best game ever So the second time I just waited for about a minute and everything was okay.
Anyway, not sure of the situation in the first time, but the second time I was in the first stage of the Penguin mode (well the stage after hitting the crane for the first time) and had Mad Hatter season 1 going when the third lock didn't seem to register. I then hit a few penguin shots and hit the crane again right before hitting the orbit. Anyway, just throwing it out there as it's happened twice in a hundred games or so.