 In the conclusion of the episode , Phineas and Ferb 's time machine is left in positive condition and available for further use at the museum . The writing staff purposely ended it this way so that they could reutilize it later in the series . A concept was eventually conceived as a way to do so , having " Phineas and Ferb go into the future and actually see Candace as an adult ( which ) drags up all kinds of memories of not being able to bust them . " This idea was used for the second season episode , " Phineas and Ferb 's Quantum Boogaloo . " 
