After a call from the General, Dick hears a voice from the phone say - "This telephone will self-destruct in two seconds" before the phone explodes. This was a spoof from the then wildly popular Mission Impossible show.
"Stop That Pigeon" was the series' name while being developed, and during that time it did not have Dick Dastardly and Muttley. The leader of Vulture Squadron was a chubby, bespectacled, and heavy-jowled Red-Baron-type character and the dog was an orange dachshund in a pilot's goggles. It appeared that these two original characters weren't going anywhere regarding story development, so Dastardly and Muttley were plucked from "Wacky Races" to star. (Klunk and Zilly were part of the developmental scheme.)
This episode was adapted into the comic book story "Mission Impassable" (Hanna-Barbera Fun-In #1, Gold Key, Feb. 1970).
(Homing missile is sensing the feather held behind Dick's back)
Dick: There's nobody here but us pigeons.
Dick: Here he comes again. Start your engines.
Zilly: I can't even start my feet.
This was the original pilot for the series but was not screened till some five weeks later.