The title and character Dangermouse were inspired by the action series Danger Man (UK).
While the voice of Stiletto was re-dubbed for US broadcast, changing his accent from Italian to Cockney, many of the quasi-Italian alliterations in his speech remained.
Baron Greenback's pet, Nero's sounds were made by recording David Jason laughing and talking gibberish, then speeding up the soundtrack.
In the pilot episode, Danger Mouse's arch-nemesis is introduced as "Baron GreenTeeth" (as opposed to Baron GreenBack, as he was known in later episodes).
When Dangermouse was shown in the US, the channel that screened it wanted the villain's accent to change from Italian to Cockney, because it might have offended Italian-Americans.
During the first series, human characters were only shown in silhouette. The secretary of the International Egg Company is modeled after Agecanonix's wife from Asterix.
Part 4 of this story uses almost non stop stock footage, not only from the first three episodes, but also Danger Mouse's rescue of Penfold from a crocodile from the opening sequence.
When The Man from Gadget (Gregios "M" Murphy) mentions the M4, he is right. The M4 is a motorway that runs from London to South Wales.
The first statue on screen is a replica of the character Ocatarinetabellatchitchix from "Astérix en Corse" (1973) by René Goscinny and Albert Uderzo
Penfold's favorite colors are yellow and black (like his tie)