This is the first episode in Season 1, and is considered the first episode of the main series.
The other kid actually goes to the same school as Timmy goes, although he is only seen in background shots.
When Timmy said it was 6:04 Vicky said it was 9:04 on the east coast which is 3 hours apart, that gives the viewers a hint they live in California (which was revealed in Christmas Every Day and Fairy Idol).
Timmy's adult version's voice is identical to the one in Channel Chasers where he turns 18. (You can notice this in the part in the jail cell when he is crying about not growing up)
The kid, the fairy messenger wanted Cosmo and Wanda to be reassigned to, could be a reference to Sid from Toy Story due to his appearance and his toy abusing personality.
Something breaking or dying whenever someone says Vicky's name.
The word creep or creepy being said after Timmy wishes to be an adult.
Characters having a shaving problem, resulting in them injuring themselves.
When Vicky sees Timmy as an adult, she becomes shocked, blows a whistle and uses karate moves on Timmy.
How did the mean kid know about fairy godparents?
After Timmy is transformed into an adult, Cosmo and Wanda's reaction was "ewwww", but watch their mouths, they are out of sync with the words and they seem to be saying something else.
How did Timmy get a car? It is impossible because Mr. and Mrs. Turner took their car to the movies.
After Timmy heard Francis' bullying Chester, he said "this looks like a job for..." then Cosmo and Wanda continued Timmy's phrase "...older Timmy", but watch the movement of Wanda's mouth, there's no teeth shown. But in later episodes, Wanda's teeth always appear when she talks.
Wouldn't Timmy have forgotten that he even HAD fairies, because according to Channel Chasers, when Timmy was 18, he didn't realize who Cosmo and Wanda were? It could be possible that this doesn't apply here since Timmy did not age himself with an actual aging device (The magic TV remotes aged people if they pressed the fast forward button on the remotes).
The kid that the fairy messenger wanted to reassign Cosmo and Wanda to showed no signs of being miserable. Later in the series, it is mentioned one of the requirements to having a fairy godparent is being a miserable kid.
The adult Timmy from Channel Chasers looks different from the adult Timmy in this episode. Although, this could be due to the fact that each couple of episodes is made by a different author.
Or, it might be because this Timmy was older than the one from Channel Chasers.
Or it could be due to the fact he aged himself by wishing and not via aging devices.