Ken Berry as Frank

Sandy Duncan as Liz

Harry Morgan as General Stilton

Roddy McDowall as Mr. Stallwood

McLean Stevenson as Link

Jesse White as Earnest Ernie

Alan Young as Dr. Wenger

Hans Conried as Dr. Heffel

Ronnie Schell as Jake (Voice) / Sgt. Duffy

James Hampton as Capt. Anderson

Howard Platt as Col. Woodruff

William Prince as Mr. Olympus

Ralph Manza as Weasel

Tom Pedi as Honest Harry

Hank Jones as Officer

Rick Hurst as Dydee Guard

John Alderson as Mr. Smith

Tiger Joe Marsh as Omar

Arnold Soboloff as NASA Executive

Mel Carter as 1st Soldier

Dal McKennon as Farmer

Alice Backes as Farmer's Wife

Henry Slate as Sandwich Man

Roger Pancake as Red

Roger Price as 1st E.R.L. Expert

Jerry Fujikawa as 2nd E.R.L. Expert

Jim Begg as Dydee Driver

Peter Renaday as Bailiff

Rickie Sorensen as Technician

Tom Jackman as Army Engineer

Fred L. Whalen as Sarasota Slim

Joseph G. Medalis as Sucker

Gil Stratton as 1st NASA Scientist

Jana Milo as 2nd NASA Scientist

Sorrell Booke as Presiding Judge (uncredited)

Jackson Bostwick as Additional Voices (voice) (uncredited)