Dexter ends up in the "old part of the lab" where his earliest inventions, long since forgotten, are not too happy to see him. They are mad at him for saying they were his greatest inventions, then moved on to another great invention.
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.