Early Installment Weirdness / The Amazing World of Gumball

• The pilot episode had both Gumball and Darwin Watterson look nothing like how they do in the series proper (Darwin was CGI instead of 2D animation, and Gumball's design was radically different). Both also had different voice actors, with Gumball voiced by Nicky Jones of Chowder fame, and the earlier designs of the other characters were rougher and less refined, some even having radically different designs.
• In the series proper, some characters had slightly or completely different personalities in season 1 than in season 2. Darwin started off being just as dumb (if not dumber) as Gumball, but eventually became the slightly naive voice of reason. Alan the balloon became an extremely Nice Guy in season 2 when, in the first season, he could be just as antagonistic toward Gumball and Darwin as the other students at the school. Then there's Sussie the chin puppet, who was a relatively normal student (who tended to drool on everything and always chewed with her mouth open, to emphasize the fact that she was a chin puppet), but became a bizarre Cloud Cuckoo Lander in season 2.
• The first season's episodes were mostly centered on Gumball, his family, and their trials and tribulations in life; some episodes were Mundane Fantastic while others were no different than what you would normally see in a Slice of Life series. Later seasons do still have these type of episodes, but are significantly Denser and Wackier, more darkly comedic, and often involve a lot of Genre Roulette. There's also a greater focus on Gumball's classmates.
• In the first season, the first ten episodes or so were animated slightly differently from the later episodes. All the episodes have mixed media, with CGI dinosaurs mixed in with claymation balls of clay, 2D flowers, and ghosts. However, the animations of the 2D characters became slightly more jerky and generally cartoony than the first episode's more lifelike motions. Gumball's body also changed in form slightly, with his fangs rounded and his eyes slightly smaller than before. All of this was changed by the first season finale, as the animations in the last two episodes seemed less jerky and more lifelike, along with Gumball's fangs being sharp again and his eyes being bigger.
• The first season featured unrefined character designs, and supporting characters (such as Bobert, Leslie, Clayton, Alan, and Anton) had their voices change erratically from episode-to-episode.
• Miss Simian in season 1 was blockier, shaded gray, and had a scratchier voice. Starting in season 2, Miss Simian's computer animation was more refined, she had a somewhat lower, yet still screechy voice, and now wears a pink dress.
• Mr. Small did not look or sound like a stereotypical hippie in season 1. In season 1, he had a slight Southern accent, was more of a parody of touchy-feely guidance counselors, and, as seen in "The Meddler," acted like a Drill Sergeant Nasty when it came to cheerleading auditions.
• The Watterson children were allowed far less independence in the first season: Excepting emergencies and sneaking out, the kids are chaperoned everywhere outside school and their own neighborhood. In "The Responsible", they're allowed to stay home without a babysitter only out of desperation, and Nicole concludes even that was a huge mistake. In "The Spoon", Nicole is enraged when she finds out Richard sent Gumball and Darwin Convenience Store Gift Shopping, though her concern could have been due to this being rather late at night. From the second season on, even Anais is allowed to stay home alone, while her older brothers regularly travel all over town, either through public transit or by foot. This overlaps with Characterization Marches On, as both Darwin and Gumball were a lot more childish in the first season, despite neither of them aging since.
• In the Season 1 episode "The Date", Anais invites Gumball into her bedroom to practice his manners for his "date" with Penny with her dolls. Later episodes show Anais sharing a room with her brothers.
• There is no Vignette Episode in the first season. It's a series staple, but it didn't appear until season 2.
• While not completely absent, there were significantly fewer adult jokes in season 1.
• Throughout Season 1, the Watterson family could be seen front facing from time to time, instead of always having their faces at a 3/4 angle.

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