Matthew Broderick

Richard Feynman

Patricia Arquette

Arline Greenbaum

Peter Riegert

Mel Feynman

Jeffrey Force

Young Richard

David Drew Gallagher

Harold

Raffi Di Blasio

Robert

Josh Keaton

David

James Hong

Abacus Adder

Melissa DeLizia

Young Joan

Peter Michael Goetz

Dr. Gell-Mann

Kelly Wolf

Nurse Kate

Mary Pat Gleason

County Nurse #2

Joyce Van Patten

Aunt Ruth

James Le Gros

John Wheeler