First episode of Phineas and Ferb to have just one plot.
Dr. Doofenshmirtz and Major Monogram each have only 1 line in this episode, as this is one of the few episodes where Perry does not have another plot away from Phineas and Ferb (or Pinky in the case of Isabella and the Temple of Sap and Bee Story).
After Linda apologizes to Candace for all the projects that she missed, she calls her "the best daughter any mother could dream of having." This is a clue that the episode is a dream.