On the episode "The Sting," when at Fry's funeral, a large women says "he makes good snusnu." and it then shows his girlfriends from the episodes. Look among their feet, there's a radiator there as in another episode, Fry says "I don't know about you, but I just made out with the radiator from the radiator planet." He is informed that there is no such thing as a radiator planet, but I guess it was real as it was there.