Fourth wall

The fourth wall is the imaginary "wall" at the front of the stage in a traditional three-walled box set in a proscenium theatre, through which the audience sees the action in the world of the play. When speaking directly to the audience through the camera in a film or television program, it is called "breaking the fourth wall." The technique of breaking the fourth wall can be seen in various television programs, especially situation comedies, in animated cartoons, and in films.

Season 1

 * When Perry is invited in by Dr. Doofenshmirtz, Agent P waggles his eyebrows while looking at the audience, in the same manner as Groucho Marx ("Flop Starz").
 * When Mom thinks the boys riding the horses is cute, Phineas looks at the audience and says "She means well" ("The Magnificent Few").
 * Dr. Doofenshmirtz ahem when the dramatic music does not come on at one point ("Run Away Runway").
 * Phineas asks where the backgrounds are coming from during Danny's Story ("Dude, We're Getting the Band Back Together").
 * Ferb says that building their Big Idea takes about a montage ("Voyage to the Bottom of Buford").
 * Perry looks directly at the camera when the elevator is broken ("Got Game?").
 * In the beginning, Phineas and Ferb are in front of a curtain and tells the audience that what they are about to see can scare, or even horrify, them. Also, Candace asks Reginald to tell the story in color ("The Monster of Phineas-n-Ferbenstein").

Season 2

 * Dr. Doofenshmirtz asks where the lightning is coming from ("Oh, There You Are, Perry").
 * Isabella and Gretchen wipe the camera during Phintastic Ferbulous Car Wash ("At the Car Wash").
 * Phineas references the use of storm clouds to show negative impact before looking at the camera ("Phineas and Ferb Christmas Vacation!").
 * An advertisement appears saying "You're watching Television!". Phineas says that it is interrupting a visual gag ("Phineas and Ferb: Summer Belongs To You!").
 * Ferb is counting the seconds from Phineas making a point that creates an idea to wondering where Perry is ("The Secret of Success").
 * One of the rooms in Phineas and Ferb's building is called the "studio audience room" ("The Doof Side of the Moon").