The waiter's, who offers Timmy a chocolate pudding, nervous facial expression when Timmy asks him which door did he come out of and the fact that he is in front of the restroom door could imply that the "chocolate pudding" is actually poop. Billy Crystal Ball even confirms that it's not pudding.
Cosmo's father's voice is similar to his son's voice from the Oh Yeah! Cartoons shorts.
Apparently Cosmo was responsible for the eruption of Mt. Vesuvius (which subsequently destroyed Pompeii), the sinking of Atlantis (done in a toilet flush style), and the destruction of Xanadu (replacing it with Pittsburgh).
This is also one of the nine times Cosmo sunk Atlantis, as it was revealed he sunk Atlantis nine times in Something's Fishy!
Cosmo has activated his wand by sucking on it so much that almost all of Fairy World are terrified of him when he does this (since almost everytime he previously did it, it caused disastrous results such as summoning a three headed dragon named Snowball that destroyed everything in its sight). This is what convinced the people of Fairy World to vote that he should stay with Timmy since they don't want that to happen again.
If you listen closely when Timmy asked who was the only person to vote that Cosmo should go back to live with his mother, when they turn to Wanda, she's whistling the Fairly Odd Parents theme song.
This is the second time Mama Cosma used a TV show (and bribed the host) to try and separate Cosmo and Wanda. The first time was in Apartnership when she bribed Cupid to break them up on his dating show.
Britney Britney can be seen as a fairy in one of the pictures with other fairies.
The Terminator - During one flashback, when Jorgen gets burnt, his eyebrows are singed off and his hair is burnt down to spikes; This is likely a reference to Arnold Schwarzenegger's appearance roughly 1/3 in the film, when the Terminator received similar battle damage due to fire. As Jorgen is heavily based on Arnold Schwarzenegger, this was likely intentional.