Fourth Wall

Breaking the fourth wall is a comedy device used in fictional stories in which a character acknowledges the fact that they are a character in a show or television show, and are actually aware of being such. There are several ways of breaking the fourth wall; examples include when a character refers to a particular part in a television episode, when a character stops others from performing an occult or criminal act by referring to the fact that it is a "children's movie/show," when a character responds to a real world person who is not physically present (such as the narrator), or when a character talks directly to the viewer.

Season 2

 * "The Apology": Gumball asks why he has to run every 8 minutes of his life.
 * "The Flakers": Anais breaks the fourth wall when she winks at the camera.
 * "The Dream": Gumball and Darwin fight over a censorship panel.
 * "The Game": Gumball pulls a card that says "Dramatic Music Until the End of the Game."
 * "The Voice": Tobias indirectly mentions how he feels like he's the supporting character of his own life.
 * "The Castle": Darwin realizes how Gumball's voice has changed.
 * "The Sweaters": Gumball mentions how the episode will end.
 * "The Finale":
 * Anais noticing that they were relatively unscathed after falling from such a large height in "The Responsible," a reference to the humorous laws of cartoon physics.
 * Richard explaining that when he is placed in prison, he is suddenly "just not in there anymore," a reference to the shift back to the status quo at the end of episodes.
 * Gumball noticing how they looked different in the family album, a reference to the transition in drawing style and animation that occurred between Season 1 and Season 2.
 * Gumball wondering why the episode looked like it would not end happily, a reference to how most episodes end happily.
 * Gumball stating that only a total reality reset could save them, a reference to how the ending of episodes tends to revert the town back to normal, also known as deus ex machina.

Season 3

 * "The Fan": Sarah breaks the fourth wall by singing the show's ending theme.
 * "The Joy": The camera squishes Miss Simian's face. Another instance is when Miss Simian asks for the time, and the time-card crashes into her.
 * "The Fraud": Principal Brown breaks the fourth wall in this episode when he points out that Gumball and Darwin's nudity is pixelated.
 * "The Allergy": Darwin sneezes on the camera, causing it to glitch up.
 * "The Safety": Gumball, Anais, and Nicole crash into a "viewer discretion" notice.
 * "The Countdown": Gumball crashing into the screen, freezing time. The fourth wall is also broken when Gumball and Darwin interact with the on-screen timer, mentioning how it took them a minute to get far out in the desert.

Trivia

 * Season 1 is the only season that does not break the fourth wall.
 * Gumball breaks the fourth wall more than any other character.