While Dick was created as the equivalent of Professor Fate from the 1965 movie The Great Race, Muttley mirrored the film's character of Max Meen.

Messick also used the same snickering chortle for "Snuggles," a mischievous dog who tormented Quick Draw McGraw; then for "Griswold" in an episode of Top Cat; then for "Mugger" appearing in the 1964 movie Hey There, It's Yogi Bear;[15] and again for Precious Pupp in 1966.

Muttley (who turned from a "bluish hue" to a "dusty brown")[15] wore only a collar in Wacky Races, but in Dastardly and Muttley in Their Flying Machines, he donned a World War I style aviator's cap and scarf, and served as a flying ace along with Dastardly and two other pilots as members of the "Vulture Squadron".

Mumbly later showed up as the captain of the villainous Really Rottens in Laff-a-Lympics along with his accomplice, "The Dread Baron," who resembles Dick Dastardly.

The Dread Baron and Mumbly later appeared in the TV movie Yogi Bear and the Magical Flight of the Spruce Goose.

The reason most suggested is that the Wacky Races characters (including Dastardly and Muttley) were not fully owned by Hanna-Barbera as the show was a co-production with Heatter-Quigley Productions.