"It's About Time!" is the twenty-first broadcast episode of the animated television series Phineas and Ferb's first season. It originally aired on Disney Channel on March 1, 2008. The episode concerns stepbrothers Phineas and Ferb fixing a time machine on display in a museum and using it to travel back to prehistoric times. Meanwhile, Perry the Platypus deals with being replaced with a panda bear as the nemesis of the mad scientist Dr. Heinz Doofenshmirtz. "It's About Time!" was written and directed by series co-founder Dan Povenmire, and storyboards were constructed by multiple artists in the show's production staff. The writers purposely left the time machine available to the boys at the end of the episode in order to reuse it later in the series, which they did in the season 2 episode "Phineas and Ferb's Quantum Boogaloo." Critical reception was generally positive, and multiple reviewers applauded Perry and Doofenshmirtz's relationship in the episode, which they noted was portrayed with possible homosexual subtext.