Son of Flubber

Fred MacMurray

Ned Brainard

Nancy Olson

Betsy Brainard

Keenan Wynn

Alonzo P. Hawk

Tommy Kirk

Biff Hawk

Ed Wynn

A.J. Allen

Charles Ruggles

Judge Murdock

Leon Ames

Rufus Daggett

Ken Murray

Mr. Hurley

William Demarest

Mr. Hummel

Paul Lynde

Sportscaster

Elliott Reid

Shelby Ashton

Bob Sweeney

Mr. Harker

Joanna Moore

Desiree de la Roche

Edward Andrews

Defense Secretary

James Westerfield

Officer Hanson

Alan Carney

Referee

Stuart Erwin

Coach Wilson

Forrest Lewis

Officer Kelly

Alan Hewitt

Prosecuting Attorney

Jack Albertson

Mr. Barley

Eddie Ryder

Mr. Osbourne

Harriet E. MacGibbon

Mrs. Edna Daggett

Beverly Willis

Mother in Commercial

Wally Boag

Father in Commercial

Russell Custer

Board Member (uncredited)

Joe Flynn

Rex Williams (uncredited)

George Ford

Courtroom Spectator (uncredited)

Byron Foulger

Proprietor (uncredited)

Darby Hinton

2nd Hobgoblin (uncredited)

Harvey Korman

Husband in Commercial (uncredited)

Dal McKennon

First Juror (uncredited)

King Mojave

Board Member (uncredited)

Burt Mustin

1st Bailiff (uncredited)

Ron Nyman

Courtroom Spectator (uncredited)

J. Pat O'Malley

Sign-Painter (uncredited)

Robert Shayne

Defense Secretary's Assistant (uncredited)

Arthur Tovey

Juror (uncredited)

Ginny Tyler

Baby Walter (voice) (uncredited)

Leon Tyler

Humphrey Hacker (uncredited)