Cranius Maximus

When Baljeet becomes concerned that he is losing his mental edge, the boys invent a cerebral stimulatory hat, or "Brain booster," to help him. But when the hat exceeds expectations and makes Baljeet exponentially smarter, he suddenly views everyone else as beneath him and becomes a threat to civilization by taking Earth's atmosphere and bringing it to the moon. Meanwhile, Dr. Doofenshmirtz plans to use his "Key-Find-Inator" to collect all the keys in Danville in hopes that it will lead to the Key to the City.

Songs

 * Taking on the Big Brain

Perry's entrance to his lair
None.

Background Information

 * http://movies.netflix.com/Movie/Phineas_Ferb/70177007?trkid=2361637
 * It is revealed that Isabella could be up to 12 years old, due to her saying, "I was so looking foward to junior high".

Continuity

 * Second time Doofenshmirtz looks for a key ("Ask a Foolish Question").
 * Third time one of Phineas and Ferb's inventions goes bad ("Day of the Living Gelatin", "Escape from Phineas Tower")
 * Candace wears the same swimsuit as she did in "De Plane! De Plane!" and "Atlantis".
 * The skyscraper from "The Doof Side of the Moon" is seen again at the dark side of the moon. This might mean this episode happened before "Moon Farm". The reason is currently mentioned in Ferb's line for that episode.

Allusions

 * Circus Maximus - The episode title is an allusion of Circus Maximus, an ancient Roman chariot racing stadium and mass entertainment venue.
 * The Adventures of Jimmy Neutron: Boy Genius - The plot of this episode is similar to "Sheen's Brain," in which Jimmy's invention causes Sheen to grow so smart that he attempts to take over the world.
 * The Chronicles of Narnia - Perry's lair entrance is the same as when Lucy enters the wardrobe and into Narnia.

Cast

 * Vincent Martella as Phineas
 * Ashley Tisdale as Candace
 * Thomas Sangster as Ferb
 * Caroline Rhea as Mom
 * Mitchel Musso as Jeremy
 * Dan Povenmire as Dr. Doofenshmirtz
 * Jeff "Swampy" Marsh as Major Monogram
 * Richard O'Brien as Dad
 * Dee Bradley Baker as Perry
 * Alyson Stoner as Isabella Garcia-Shapiro