Dean Jones as Professeur Albert Dooley

Sandy Duncan as Katie Dooley

Joe Flynn as Finley Hooper

Tony Roberts as Fred Hines

Lee Montgomery as Jimmy Dooley

Jack Kruschen as Doctor Gottlieb

Virginia Vincent as Eunice Hooper

Jack Bender as Arvin Wadlow

Billy Bowles as Orlo Wadlow

Sammy Jackson as Frisby

Arthur Hunnicutt as Mr. Purdham

Frank Wilcox as Mr. Meaker, the Bank Manager

Bryan O'Byrne as Bank Teller

Bing Russell as Mr. Smith

Peter Renaday as Mr. Beckert

Frank Cady as Assayer

George O'Hanlon as Parking Attendant

Jonathan Daly as Carter - Purchasing Agent

Hal Smith as Courthouse Guard

Edward Andrews as Morgan

Howard Culver as Morgan's Assistant (uncredited)

Maurice Dallimore as Englishman (uncredited)

Bernard Fox as Car Salesman (uncredited)

Arthur Franz as Prosecutor (uncredited)

Jerry Fujikawa as Japanese Official (uncredited)

Jonathan Hole as Refinery Agent (uncredited)

Hank Jones as Commencement Speaker (uncredited)

Jack Perkins as Agitated Driver #2 (uncredited)

Roy Roberts as The Judge (uncredited)

Fran Ryan as Mrs. Purdham (uncredited)

Jeffrey Sayre as Man in Refinery Office (uncredited)

Robert Shayne as Refinery Executive (uncredited)

Vaughn Taylor as Bank President (uncredited)

Bruno VeSota as Russian (uncredited)

Ted Jordan as Mr. Forbes

James Gregory as Rutledge