In addition to managing several business ventures, he made appearances at comic book conventions and collectors' shows worldwide.

This kicked off Duncan's career as a movie swing dancer and actor and led to numerous appearances in other films, and a contract with 20th Century Fox, where he appeared in productions with Shirley Temple and Jane Withers.

[2] He later appeared in bit parts in a number of films including Plan 9 from Outer Space.

He played a member of The Black Rebels Motorcycle Club in the classic Marlon Brando film The Wild One in 1952.

[2] Duncan made occasional appearances at movie conventions, often signing photos from The East Side Kids and Batman and Robin until his death in February 2016 at the age of 92.