Errors

These are the mistakes on Phineas and Ferb whethers its the laws of phyics or worse the law

Rollercoaster
In "Phineas and Ferb's Quantum Boogaloo", Candace states that this date was the first day of the summer, but Mrs. Flynn states that Candace told her about another of the boys' ideas, making it at least the second day. Although it may have happened after the last day of school.

Dude, We're Getting the Band Back Together

 * Linda asks Lawrence if he knows what day it is. Lawrence replies that it's Thursday. Linda leaves in a huff. When Candace pulls out the calendar, she points to June 15th, which is on a Tuesday (or Wednesday, if the calendar were starting on Mondays).
 * Why is Swampy stamping books that have been returned "Overdue?"
 * Phineas calls Isabella to ask her for help on putting up the stage. She and the Fireside Girls are "already on it," building a stage in front of the garage. Later, when Laurence is commiserating over the failure of the "Love on the Run" plan, Phineas and Ferb come in to tell him they've got it covered. They open the garage to reveal the members of Love Händel, but there is no sign of a stage in front of the garage.
 * Later, when the band walks out on the stage, it's elevated, but the garage is at ground level.

Bowl-A-Rama-Drama

 * Do svindanya" is actually a Russian phrase (meaning goodbye) not from Mexico as Doofenshmirtz said.

Isabella and the temple of sap
It is beyond illegal for a person to drive under the age of 16 espically without a learners' permit and an adult in the car

What do it do?
On the drive-in date flashback, Doofenshmirtz's white disco coat turns green when he gets in the car, but goes back to white when the scene changes to the outside POV (when Linda tells him to get the car speaker).

Phineas and Ferbs' Hawiian Vacation
All animals entering the State of Hawaii must undergo a period of quarantine. It's unlikely that Perry would have been allowed into the state at all.

Phineas and Ferb Summer Belongs to you
Stealing a bike is extremmley illegal it is possiable that Buford could have been arrested after the episode cause he still has the 1 with the large wheel