Phineas and Ferb's Quantum Boogaloo, Phineas and Ferb Musical Cliptastic Countdown

Phineas and Ferb travel to the future to find a tool that hasn't been invented yet, and run into future Candace. Seeing an opportunity to finally bust her brothers, she follows them back through time to catch them building their rollercoaster, and exposes their antics to her mom. In the process, she accidentally foils Agent P's defeat of Dr. Doofenshmirtz, starting a chain reaction that turns the future into a dystopian society.
Major Monogram and Dr. Doofenshmirtz host this special episode counting down the top 10 most popular music videos from the show's first season as voted by the fans and viewers, but not without the evil doctor attempting to pull off another scheme to gain power. Fortunately, Perry the Platypus is there to save the day.