After you’ve cleared all the Mystery Spot shots, it says Shoot the Super (or something like that). I shot Otto, but no dice. Had Itchy/Scratchy stacked, so there were already flashing yellow arrows everywhere.
Two shots to the garage: one to open it, then another one quickly to score the super. Additionally, if you have the super lit/ready when you drain out of MS, the garage door briefly opens for a shot at a grace period super! That’s actually how I got my first and only (so far) SDMEWM…super friendly grace period super for my last requirement!
EDIT: I defer to KCB.
If you’re really feeling like hot stuff but also hate trying to open the door and cash in the super jackpot, you can always try the “Do or Die” super jackpot strat: trap a ball on each flipper, then flip one into the drain while leaving both flippers up. When the garage door opens, that means that the flippers have reverted to the non-reversed state and you have two or three seconds to snag the quick non-reversed MS super!
Disclaimer: I’m not responsible for the damage caused by putting your fist through the glass when you go for this and it doesn’t work out. Not that I know first hand about ever missing the super this way…nope.