History EarlyInstallmentWeirdness / TheFairlyOddParents

** If Timmy, Chester or AJ lose all their lives in the video game world, they would die for good. Later episodes would establish that fairy magic can't be used to kill/seriously harm someone.

* In "[[Recap/TheFairlyOddParentsS1E2PowerMad Power Mad!]]", Cosmo and Wanda need to use human electricity to power their wands for an especially complicated wish. In any other episode after that one, they draw their power from the tower in Fairy World.

** Timmy was far more of a [[DeadpanSnarker sarcastic]] StraightMan compared to his more optimistic personality seen in the final show. He was also voiced by Creator/MaryKayBergman in the original shorts. When the series was picked up, Timmy was voiced by Creator/TaraStrong due to Bergman's death. However, when the shorts were re-aired on television, Strong's voice was re-recorded over Timmy's lines.

* In "[[Recap/TheFairlyOddParentsS1E7FatherTime Father Time]]", Timmy uses the heat vision he wished for earlier to win a race. The second season would introduce the "can't use magic to win a competition" rule.

** In "[[Recap/TheFairlyOddParentsS0E1TheFairlyOddParents The Fairly OddParents!]]" pilot Timmy had red hair the same shade as Vicky's, in every other episode Timmy's hair is brown. WordOfGod is that this was to changed to prevent Timmy and Vicky from being mistaken as siblings.

*** In the first season alone, Cosmo and Wanda were then turned into a pair of [[{{Keet}} cheerful]] [[CloudCuckooLander wacky]] fairies ("two halves of a whole idiot"). With "[[Recap/TheFairlyOddParentsS1E4TransParents Transparents!]]" showing Wanda, being nearly as much of a Cloudcuckoolander as Cosmo and does just as mediocre a job as Cosmo at trying to act like a human.

*** Vicky and Tootie's relationship was also different compared to the final show; Vicky actually stands up for Tootie, something modern Vicky would outright never do, and she even brings Tootie to Timmy's house while Timmy is recovering from his allergy attack.

** Cupid's appearance in the ''Oh Yeah!'' short "The Zappys" depicts him as blonde, gigantic, overweight and wearing little besides a diaper.[[note]]though this design does appear on and off again in the series proper, notably the episode "The Same Game"[[/note]] In the series proper, he looks more like a standard fairy, has pink hair and wears a pink coat in addition to a diaper.
** The Crimson Chin's first appearance is in the final ''Oh Yeah!'' short "Super Humor", where he notably lacks the black spot underneath the C insignia on his chin that he'd be depicted with in the actual series.
** A few title cards in the ''Oh Yeah!'' shorts ("Too Many Timmys" and "The Temp!") were animated, and one had no title card at all ("The Fairy Flu"), just the title on a moving image. The show proper used static title cards for all its non-special episodes (except "Super Bike" and "Old Man and the C-")

* In "Power Mad!", Cosmo and Wanda need to use human electricity to power their wands for an especially complicated wish. In any other episode after that one, they draw their power from the tower in Fairy World.

* In "A Wish Too Far", Trixie briefly mentions having a mother. Later episodes imply that her father is a single parent (he shows up often with no wife in sight).
* In the first season episode "Father Time", Timmy uses the heat vision he wished for earlier to win a race. The second season would introduce the "can't use magic to win a competition" rule.

* Speaking of Dinkleberg, in "Fairy Friends and Neighbors" Mr. Turner actually invited Dinkleberg over, and it was the latter who wasn't interested this time around.

** Vicky's sister Tootie had a noticeably different design during her debut in the Oh Yeah! Cartoons short "[[h/Recap/TheFairlyOddParentsS0E5TheFairyFlu The Fairy Flu]]". Her head was more oval-shaped, her pigtails were a different shape, she wore pink glasses frames as well as a blue dress and she didn't have braces.

** In the shorts, Jorgen was portrayed as a regular Fairy Godparent (with a very scared godson) instead of being an authority figure of Fairy World.

** Cosmo's and Wanda's current personalities were reversed: Cosmo being the more down to earth one and Wanda being the ditzy spouse, though neither really came across as dumb (contrast crazy and stupid). Cosmo also had a more smooth baritone Phil Hartman impersonation, which even the start of the official series had distanced from for an increasingly shrill, helium pitched voice.
** Vicky acted more like a bossy normal teenage girl, with the worst she did was give Timmy chores to do and take away his fun (like forbidding him to watch TV until his chores were done) and {{Blackmail}} him. A far cry from her more well-known charactization of being a [[AxCrazy crazed psychopa]] who tries to ''[[WouldHurtAChild kill Timmy]]''.

* In the first season, Timmy was the OnlySaneMan, Cosmo and Wanda were a pair of [[{{Keet}} cheerful]] [[CloudCuckooLander wacky]] fairies ("two halves of a whole idiot"), Cosmo's voice was deeper and sounded more like a gameshow host (WordOfGod said he was supposed to sound like a used car salesman), and Vicky feared her parents.

* In the original ''WesternAnimation/OhYeahCartoons'' shorts, the animation was a lot cruder and it seemed that Jorgen was a regular Fairy Godparent (with a very scared godson) instead of being an authority figure of fairy world. And Timmy's parents were the type of cartoon character who [[TheFaceless only ever appear onscreen from the shoulders down]].
* A few title cards in the ''WesternAnimation/OhYeahCartoons'' era were animated, and one had no title card at all, just the title on a moving image. The show proper used static title cards for all its non-special episodes (except "Super Bike")
* In early seasons, Timmy losing his fairies didn't include having his memories erased. It wasn't until the Season 3 episode "The Secret Origin of Denzel Crocker!" that this became an aspect of losing one's fairies.
* Vicky mentioned having a little brother in the first ''WesternAnimation/OhYeahCartoons'' short. However, he was subsequently [[{{retcon}} replaced]] with a little sister, Tootie.
* In the first season episode "Father Time", Timmy uses the heat vision he wished for earlier to win a race. The second season would introduce the "can't use magic to win a competition" rule.

* In "Spaced Out!", Cosmo and Wanda "borrowed" Mark Chang after Timmy wished for an alien for his friends to play with, claiming that they can't create an alien out of nothing. In later episodes, creating entire ''eco-systems'' out of nothing is almost not worth mentioning, since it happens so often.

* Speaking of Dinkleberg, in "Fairy Friends and Neighbors" Mr. Turner actually invited Dinkleberg over, and it was the latter who wasn't interested this time around.

* In the original ''WesternAnimation/OhYeahCartoons'' shorts, the animation was a lot cruder and it seemed that Cosmo's and Wanda's current personalities were reversed: Cosmo being the more down to earth one and Wanda being the ditzy spouse, though neither really came across as dumb (contrast crazy and stupid). Jorgen was a regular Fairy Godparent (with a very scared godson) instead of being an authority figure of fairy world. And Timmy's parents were the type of cartoon character who [[TheFaceless only ever appear onscreen from the shoulders down]].

* Timmy was also voiced by Creator/MaryKayBergman in the original shorts. When the series was picked up, Timmy was voiced by Creator/TaraStrong due to Bergman's death. However, when the shorts were re-aired on television, Strong's voice was re-recorded over Timmy's lines.
* In the original shorts, Da Rules book was yellow instead of purple.
* In one of the pilot shorts, BatmanCanBreatheInSpace was played straight. The show proper would avert this.