Flug is a planet renowned for its champion.
Flug can be reached from Mertz if a left turn is taken at Andromeda. (Whether this means the Andromeda Galaxy or a planet named Andromeda is unclear.) Failing to do so might end one up on Earth. Flug is known for having an ace champion who occasionally agrees to take a starting or bumbling hero as apprentice.
Comet Guy was supposed to go to Flug to receive hero training from its champion, but ended up on Earth instead. Only after getting his degree from Darkwing Duck does he realize his error. Saying goodbye, he mans his spaceship and leaves for Flug.