Ken Berry

Frank

Sandy Duncan

Liz

Harry Morgan

General Stilton

Roddy McDowall

Mr. Stallwood

McLean Stevenson

Link

Jesse White

Earnest Ernie

Alan Young

Dr. Wenger

Hans Conried

Dr. Heffel

Ronnie Schell

Jake (Voice) / Sgt. Duffy

James Hampton

Capt. Anderson

Howard Platt

Col. Woodruff

William Prince

Mr. Olympus

Ralph Manza

Weasel

Tom Pedi

Honest Harry

Hank Jones

Officer

Rick Hurst

Dydee Guard

John Alderson

Mr. Smith

Dal McKennon

Farmer

Alice Backes

Farmer's Wife

Henry Slate

Sandwich Man

Jerry Fujikawa

2nd E.R.L. Expert

Jim Begg

Dydee Driver

Peter Renaday

Bailiff

Joseph G. Medalis

Sucker

Gil Stratton

1st NASA Scientist

Sorrell Booke

Presiding Judge (uncredited)

Jackson Bostwick

Additional Voices (voice) (uncredited)