[1] George Lamarro is the head of a pharmaceutical company that is also involved in the production and distribution of illegal narcotics.

[1] Avenger X was based on the comic series Mister-X as created by writer Cesare Melloncelli and drawing artist Giancarlo Tenenti.

[1] Unlike other fumetti neri of the era, Mister-X had very little violent content, with the titular character being a gentleman thief similar to Arsène Lupin.

[2] Parts of the film were shot in Rome including location shooting at the Stadio dei Marmi.

[2] Censors documents only suggested that 47 seconds of the film were cut in Italy[2] This included scenes where a blowtorch approaches Mister-X's bare chest and a shot of a speedboat moving towards a reef.