• 
  Blake Edwards

  CIC man
• 
  Hume Cronyn

  Dr. J. Robert Oppenheimer
• 
  Joseph E. Bernard

  Orăşean
• 
  Larry J. Blake

  Tough MP
• 
  Erville Alderson

  Secretary of War Henry Stimson
• 
  Wedgwood Nowell

  Industrialist
• 
  Carlyle Blackwell Jr.

  Armed guard
• 
  Chris-Pin Martin

  Mexican man

• 
  Selmer Jackson

  Senior engineer
• 
  Damian O'Flynn

  C.D. Howe
• 
  Trevor Bardette

  Clinic doctor
• 
  Frank Baker

  Canadian officer
• 
  Budd Fine

  Evictee
• 
  Edward Earle

  Charles G. Ross
• 
  Forbes Murray

  Briefing officer

• 
  Henry O'Neill

  Gen. Thomas F. Farrell
• 
  Hans Schumm

  Nazi police officer
• 
  Frank Wilcox

  Dr. W.H. Zinn
• 
  Bill Hickman

  Barometric observer
• 
  Norman Lloyd (I)

  Dr. Troyanski
• 
  Jim Davis

  Pilot at Tinian
• 
  Martin Kosleck

  Dr. O.E. Frisch
• 
  Russell Hicks

  General
• 
  Carl Saxe

  German general's aide
• 
  John Litel

  K.T. Keller
• 
  Torben Meyer

  Milkman
• 
  Patricia Medina

  Mrs. Wyatt (Englsh laboratory assistant)
• 
  Walter Baldwin

  Workman
• 
  William Tannen

  Loudspeaker voice
• 
  Jonathan Hale

  Dr. Vannevar Bush
• 
  Audrey Totter

  Jean O'Leary
• 
  Hurd Hatfield

  Dr. John Wyatt
• 
  Richard Loo

  Japanese officer
• 
  Charles Trowbridge

  Walter S. Carpenter Jr.
• 
  Stanley Blystone

  Civilian guard
• 
  Roger McGee

  Scientist
• 
  Richard Haydn

  Dr. Chisholm
• 
  Paul Harvey

  Lt. Gen. W.D. Styer
• 
  Brian Donlevy

  Maj. Gen. Leslie R. Groves
• 
  Joseph Calleia

  Dr. Enrico Fermi
• 
  Warner Anderson

  Capt. William S. Parsons
• 
  Victor Francen

  Dr. Marre
• 
  Edward Edwards

  CIC man
• 
  Barry Nelson

  Col. Paul Tibbetts Jr.
• 
  Tom Drake

  Matt Cochran
• 
  Godfrey Tearle

  President Roosevelt
• 
  Beverly Tyler

  Anne Cochran
• 
  Robert Walker

  Colonel Jeff Nixon

• 
  Hans Peters (I)

  art director
• 
  Cedric Gibbons

  art director
• 
  Ray June

  imagine
• 
  Daniele Amfitheatrof

  departament sunet
• 
  Irene

  costume
• 
  George Boemler

  montaj
• 
  Samuel Marx

  producător
• 
  F. Keogh Gleason

  set decorator
• 
  Edwin B. Willis

  set decorator
• 
  Douglas Shearer

  sound department
• 
  Donald Jahraus

  special effects
• 
  Warren Newcombe

  special effects
• 
  A. Arnold Gillespie

  special effects
• 
  Frank Wead

  scriitor
• 
  Robert Considine

  scriitor