Comedy actor Paul Lynde, best known for his appearances on The Hollywood Squares (Daytime) (1965) was uncredited as the voice of Sylvester Sneekly/The Hooded Claw.
Originally, the villains on the series were supposed to be Dick Dastardly and his dog Muttley. However, they were spun off onto their own series El escuadrón diabólico (1969).
Contrary to popular belief, the Ant Hill Mob in this series is not the same Ant Hill Mob that was in Hanna-Barbera's previous cartoon series, Los autos locos (1968). While there are still seven members of the Mob and they are drawn in a similar style, there are enough differences in both appearance as well as names to indicate that these are two separate groups. The car used by the Mob ("Chug-a-Boom") is also of a different design than the car (the 'Bulletproof Bomb') in the Wacky Races.
The members of the Ant Hill Mob are Clyde (the leader), Dum Dum, Pockets, Snoozy, Softy, Yak Yak and Zippy.
When looking at the original recording scripts, it becomes apparent that the episodes would originally feature an introduction to the story before the 'when we last left Penelope' bits. This explains why some episodes feature plot points that were never explained, like the phone call in Wild West Peril (1969).