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 theater, through which the audience sees the action in the world of the play. When a character makes direct contact to the audience from a film or television program or references his or her status of being in one, 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.

Opening credits & other media

 * The theme song ends with Candace pointing out that "Phineas and Ferb are making a title sequence."
 * In a similar matter, Candace points out "Mom, Phineas and Ferb are having a Marathon with Zack and Cody!" During an ad for the "If it's not one thing, it's your brother" marathon.  She also points out "Mom, Phineas and Ferb are changing the name of a month!" during "Phineas and Ferb-uary"
 * In the same manner, Candace points out that "Mom, Phineas and Ferb are making a Christmas special!" at the end of the title sequence unique to "Phineas and Ferb Christmas Vacation!".
 * Also in the same manner, Candace yells out that "Mom, Phineas and Ferb are making a Halloween special!" after the title sequence for "That's the Spirit" as well as "Druselsteinoween", "Terrifying Tri-State Trilogy of Terror" and "Face Your Fear". This was repeated in the episode opening of "For Your Ice Only"/"Happy New Year!" where she points out that they're making another winter-themed opening.
 * In the title sequence of Phineas and Ferb: Mission Marvel, Spider-Man parodies Candace's line as, "Aunt May, Phineas and Ferb are making a crossover!"
 * In an ad where Phineas narrates about the dangers of the internet universe, in the same manner, Candace points out that "Mom, Phineas and Ferb are making a public service announcement".
 * On the Phineas and Ferb Disney Channel old website, upon going there, Candace can be heard saying, "Mom, Phineas and Ferb are building a web site!"
 * At the end of the Take Two with Phineas and Ferb theme song, Candace says, "Mom, Phineas and Ferb are making a talk show!"
 * On the "Across The 2nd Dimension" DVD, one of the Easter eggs has Candace pointing out, "Mom, Phineas and Ferb are making a DVD!"
 * On an ad for Disney's Phineas and Ferb: The Best LIVE Tour Ever!, Candace shouts, "Mom, Phineas and Ferb are making a live stage show!"
 * In the original pitches title song, Phineas says, "Don't try this at home", after the line, "Giving a monkey a shower". Also after the line, "Driving our sister insane", Phineas says, "It's a short drive".
 * In Where's My Perry?, Carl says before a level  Sir, do you want me to introduce this level? so Carl must know they are in a video game.

Season 1

 * 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 clears his throat to prompt the running of a dramatic musical string that has failed to run on cue. ("One Good Scare Ought to Do It!").
 * In the same episode, during the song "Candace (Who's That Girl)", when the singer sings a particularly long line, Candace looks at the camera annoyed.
 * Phineas is wondering where the backgrounds in the song History of Rock are coming from. ("Dude, We're Getting the Band Back Together").
 * Ferb mentions that their projects would usually be finished after a montage. ("Voyage to the Bottom of Buford")
 * Perry looks directly at the camera after noticing that the elevator is broken. ("Got Game?")
 * In the beginning, Phineas and Ferb are in front of a curtain warning the audience that they may be emotionally scarred by the coming episode. Later, Candace asks Reginald to tell his story of their ancestors in color. Phineas suggests muted color instead. ("The Monster of Phineas-n-Ferbenstein")
 * While dancing under the effect of the Dance-Inator, Dr. Doofenshmirtz speaks to the audience telling them that the platypus is leading. ("Out of Toon")
 * When Perry is invited in by Dr. Doofenshmirtz, Agent P waggles his eyebrows while looking at the audience, in a manner similar to that of Groucho Marx. ("Flop Starz")

Season 2

 * When Dr. Doofenshmirtz shows Perry the invention, he says "Behold... beholding, beholding, beholding, and scene!" ("The Chronicles of Meap")
 * In the credits of that same episode, after Meap puts on his hat, he looks at the camera.
 * 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!").
 * Candace tells someone in the show's audience to hang up ("Candace's Big Day").
 * When Dr. Doofenshmirtz is showing his De-Evolutionator, he says, "Can you all see in the back row," to the audience ("Phineas and Ferb Hawaiian Vacation").
 * An advertisement appears saying, "You're watching Television!". Phineas says that it is interrupting a visual gag. Later, Phineas says "No matter where we go, Ferb knows everyone". He is talking to the audience. ("Phineas and Ferb Summer Belongs to You!")
 * Following the Evil Jingle Segment that says "Doofenshmirtz Wicked Witch Castle!", Doofenshmirtz says "It's not Witch! It's Warlock! Argh!". At the end, Phineas says "Have fun, everybody!" to the audience. ("Wizard of Odd")
 * One of the floors in Phineas and Ferb's building is called the "studio audience floor" ("The Doof Side of the Moon").
 * After seeing an ad for an all-terrain vehicle, Ferb counts "Two, three, four..." and Phineas says that they know what they're going to do today, then after counting "Five, six, seven...", Phineas asks where Perry is. ("The Secret of Success")
 * Carl replied Major Monogram that Phineas and Ferb is a cartoon and Major Monogram reminds Carl to not break the fourth wall ("Make Play").
 * Phineas breaks the fourth wall by saying he and Ferb should build a rollercoaster as a musical, and acknowledges that people are breaking into spontaneous song and dance with no discernible music source. He also states to Isabella that Ferb had two lines earlier on, to which she responds, "Wow, chatty." Buford calls the boys with the flyers "extras." Also, Doofenshmirtz acknowledges the cut to black at the end of the first act. Major Monogram also breaks the fourth wall by saying "Come on!" when the end logos pop up. ("Rollercoaster: The Musical!")
 * Major Monogram breaks the fourth wall by calling Cindy an animated member of the studio audience. ("Phineas and Ferb Musical Cliptastic Countdown")
 * Dr. Doofenshmirtz complains about the festival being so loud that he can't hear his own evil jingle ("Attack of the 50 Foot Sister")
 * Perry looks at the camera angrily after a briefing from Monogram which he said to be careful about the paper ("Backyard Aquarium").
 * Ferb saying the episode is 11 minutes in his oath. ("The Lizard Whisperer")

Season 3

 * Baljeet talks with Buford about the opening titles, especially giving a monkey a shower. Later on, he questions how everyone is running in slow motion. ("Canderemy")
 * Candace mentions that Phineas has a catchphrase to say. ("Run, Candace, Run")
 * Baljeet argues with the male singer from Moon Farm. ("Moon Farm")
 * After Doofenshmirtz exclaims to Perry that they're not in a sitcom, they stare directly at the camera nervously supposedly realizing that his statement is false. ("A Real Boy")
 * Phineas says, "We'll be right back" before a commercial break, and fixes the time of day his flashback is being shown. He also comments on the time of day in the flashback. ("My Fair Goalie")
 * There were numerous references of Phineas' Birthday Clip-O-Rama! being a clip show in the episode, mainly by Phineas and Doofenshmirtz.
 * Ferb looks at the camera while saying, "Our dad sells antiques". ("Ferb Latin")
 * Ferb states that Perry is having a "ripple dissolve" and he must be having a flashback. Phineas then comments on how he can't see the flashback. ("Doof Dynasty")
 * Doofenshmirtz, after saying that's he's an evil genius, looks at the camera and tells us "For realsies this time!" ("The Remains of the Platypus")   The same line was used in a Disney Channel on-air promo for "Where's Perry?"
 * In the same episode, Buford says, "And...scene" to end the story.
 * When Candace asks what the Perry-Tronic does, Phineas says the theme song would explain everything. ("Mom's in the House")
 * Later in that episode, Candace points out she now has to "But-but-but".
 * When the pictures of Perry in a hat start showing, the Totally Tools Executive asks to rewind when he sees the picture with Perry in a fedora pass. ("Perry The Actorpus")
 * After the break, as Meap and Doofenshmirtz were falling to their doom, Meap says that they were falling for a long time, and Doof said, "Oh sure, a joke about the commercial break. That's how I want to spend my last few seconds!" ("Meapless in Seattle")
 * Also, in the same episode, one of the scenes that was supposed to be included was Suzy Johnson fighting Meap in the Bango-Ru convention. This scene also appeared in the fake trailer for "Meap Me in St. Louis" during the credits, and Doofenshmirtz said "Hey, wait a minute. Wasn't that Suzy stuff supposed to be in this one?"
 * When everybody around Candace transforms in to babies at the end of the episode, Candace replies, "This had better wear off before the next episode". ("Agent Doof")
 * Candace speaks to herself through inner thoughts. ("Sleepwalk Surprise")
 * Also in this episode, Doofenshmirtz goes to sleep, and just as he nods off, says that a "ripple dissolve [is] imminent."
 * Candace says "Heavenly light, angelic chorus!" ("Tri-State Treasure: Boot of Secrets")

Season 4

 * Buford tells us there's that there is a song about the Van Stomms failing as he falls toward Earth. ("Bully Bust")
 * Doofenshmirtz tells the audience in the same episode that everything was okay after the top of his building fell in the desert before the dental hygene themed ride crashes atop it.
 * Doofenshmirtz also says that the summer has been going on for like four years in the same episode.
 * When first climbing to the train roof, Doofenshmirtz says to the camera, "You knew we'd end up here eventually, right?" ("Sidetracked")
 * In the same episode, Monogram directly addresses the viewers during the credits scene.
 * As Doofenshmirtz and a hatless Perry (referred to as "Steven") head over a waterfall at Danville Botanical Gardens, Doofenshmirtz realizes that there is a commercial break coming, openly wondering why it's called a cliff-hanger not a cliff-faller and waiting for it to fade to black. ("Primal Perry")
 * Candace says that it's been a long summer. ("Mind Share")
 * In the same episode, during the Shawshank parody, both Buford and Baljeet have a conversation with Red's narration.
 * Parry Gripp is introduced by Phineas ("Backyard Hodge Podge").
 * Phineas tells us his big idea after a wipe ("Bee Day").
 * Esmeralda Poofenplotz begins her backstory with her saying "Now pay attention as the camera slowly moves closer and we cross-dissolve to my thoughts". ("Bee Story")
 * Same episode Gretchen warns Isabella to not do the flashback. Later, she interrupts her own flash-forward by wondering where Pinky is.
 * Major Monogram wonders whether Kelly Osbourne is a little too "three-dimensional" to host an animated show. ("Phineas and Ferb Musical Cliptastic Countdown Hosted by Kelly Osbourne")
 * Perry looks annoyed at the camera while Doofenshmirtz rolls around in his glass dome. ("Happy Birthday, Isabella")
 * In "Phineas and Ferb: Mission Marvel", Doof complains about Perry just kicking him once and then destroying his inator and says, "I thought this was going to be a special extended episode."
 * In the end credits, Stacy talks to the screen about Candace's book. ("Troy Story")
 * Mr. Macabre talks directly to the viewer. During the end credits, when Rusty Bridges trips on the front step and falls on his face, he encourages the viewer to read the credits while he's down and mentions the production logo coming up. ("Terrifying Tri-State Trilogy of Terror")

Phineas and Ferb The Movie: Across the 2nd Dimension

 * In the song Everything's Better with Perry, Phineas and Ferb broke the fourth wall by staring at the camera.
 * In the song Brand New Best Friend, Dr. Doofenshmirtz and his second dimension counterpart mention Lorenzo Lamas playing Meap in "The Chronicles of Meap".
 * In Summer (Where Do We Begin?), Phineas' eyes stare directly at the screen.
 * At the beginning of the cut song Mysterious Force, Candace sings directly to the audience.
 * Phineas "cut-corners" by saying "Bla bla bla, two car garage etc. etc." in the scene where the movie started. Ferb does this also by saying "Whoa. Deja-vuish.".