Dexter uses radiation therapy so he can like vegetables, it actually causes him to only eat vegetables, also, the therapy has consequences if Dexter goes too long without them. He turns into a Parody of The Incredible Hulk without vegetables.
Mandark doesn't know that his pet duck is really Quackor the Fowl, Monkey's rival. Quackor overhears Mandark talking in his sleep about destroying Dexter's lab and tries to do it, unaware that Monkey is Dexter's pet.