The Villain's Auto-Foil

Stop telling everyone your evil plan on national television already, you moron!

The Hero and their friends are at the Lowpoint, the Villain is close to winning in the fight of the Climax, and all seems lost. Just when you think no one can stop the Villain from succeeding in their plan, The Problem Solves Itself as they, using whatever nearby methods there are, accidentally reveal their plan to the Innocents. Said method can be a PA system, TV (like what the slidetext said), radio, a jumbotron, or any other way a message can be instantly sent out to hundreds of people. For this Auto-Foil to work, the Villain needs to be a Shock Villain so nobody already knows they're up to no good. Now with the Innocents knowing the one they once thought to be good turns out to really be bad, they're upset at the Villain for lying to them and start a riot that begins the Villain's Downfall. A little later, the Good Guys win the day and all ends happily.

The Villain's Auto-Foil can also not happen immediately as the Hero could be using some audio-recording device they can use to capture the Villain's confession that they will later use to share with someone who can get the Villain under arrest.