Obsada:

• Brian Dennehy Gen. Leslie Groves
• David Strathairn J. Robert Oppenheimer
• Michael Tucker Leo Szilard
• Hume Cronyn James F. Byrnes
• Richard Dysart President Harry S. Truman
• Hal Holbrook Gen. George Marshall
• Barnard Hughes Secretary Stimpson
• John McMartin Dr. Arthur Compton
• David Ogden Stiers President Franklin D. Roosevelt
• Anne Twomey Kitty Oppenheimer
• Lawrence Dane
• Ron Frazier Colonel Pash
• Olek Krupa Edward Teller
• Bernie McInerney
• John Pielmeier Seth
• Ken Pogue Groves's Commanding Officer
• Gary Reineke Dwight D. Eisenhower
• Alan Scarfe
• John Seitz
• Tony Shalhoub Enrico Fermi
• Ester Spitz Trude Weiss
• Ron White Colonel Nichols
• Stephan Balint Eugen Wigner
• Peter Boretski Albert Einstein
• Patrick Breen Richard Feynman
• Vlasta Vrana Hans Bethe
• George Popovich Samuel Goudsmit
• Lorne Brass Klaus Fuchs
• Michael Sinelnikoff Lord Rutherford
• Graham Haley Haakon Chevalier
• Fritz Buchinger Dr. Vincent
• Kliment Denchev Michael Polanyi
• Diana Fajrajsl Ilse Polanyi
• Timothy Webber Colonel Lansdale
• Harry Standjofski Robert Wilson
• Lia Sargent Mrs. Wisnovsky
• David Gow Jack Wisnovsky
• Michael Farrell Shapp
• Isabelle Mejias Mrs. Trowbridge
• Jonathan Wise Robert Serber
• George R. Robertson Ed Condon
• Dee McCafferty William 'Deke' Parsons
• Tom Butler Captain DeSilva
• Robert Morelli T.O. Jones
• Jon Baggaley James Tuck
• David Bolt Harry Gold
• David Ferry Army Major
• Heinar Pillar Fleischmann
• François Klanfer Haagen Kistiakowski
• Joel Miller George Kistiakowski
• Michael J. Reynolds Kenneth Bainbridge
• Ed McGibbon Admiral William D. Leahy
• Nick Kilbertus Paul Tibbets
• Joe Cazalet Air Force Guard
• Scott Thomson Chemist
• Bob Clout Alfred MacCormack
• Roland Hewgill Army General
• Stan Gibbons John J. McCloy
• Terrence Labrosse Allan Dulles
• Delise Alison London Pedestrian
• Alex Guard British Jr. Officer
• Philip Spensley British Sr. Officer
• Frederick Neumann Alexander Sachs
• Norris Domingue General Pa Watson
• Steve Barry Los Alamo Scientist
• Arthur Holden Scientist