Three of the Globetrotters' abilities strongly resemble that of "The Impossibles," another Hanna-Barbera cartoon group of superheroes that aired during the 1960s. Coil Man, Multi-Man and Fluid Man made up the part-time rock band/part-time crimefighting team. Their powers were retconned into Spaghetti Man, Liquid Man and Multi-Man of the Globetrotters.
Although Nate Branch's superhero identity is called "Liquid Man", he has a large "F" on the chest of his costume. It seems that the character was originally named "Fluid Man", but this was too close to a character from "The Impossibles" with the same name and super powers. It's possible that the show creators had time to change the dialogue, but not the character design.