During World War II, there were no passenger car assembly lines in operation. As a result, Vidor had to borrow cars from Chrysler, take them apart and re-assemble them in a simulated assembly line. Seen emerging from the factory are 1942 Plymouths with a Danton insignia and hubcaps. These were the last passenger cars manufactured by Chrysler before the World War II shutdown.
The two B-17s shown taxiing out and flying (they shot the takeoff from different angles to make it look like more planes) were serial numbers 42-107229 and 42-107230. Both went into combat: 42-107229 with the 447th Bomb Group, lost August 25, 1944 (ditched and sank, the crew was rescued); 42-107230 with the 100th Bomb Group, damaged on mission to Mainz, France, salvaged December 5, 1944.
After the world premiere in Cincinnati, Ohio, the New York Office of M-G-M ordered 30 minutes to be cut from the film, since exhibitors complained about its length. In his autobiography, King Vidor says he expected the cuts to come out of the documentary footage in the film, but that footage was already wedded to the music. So the cuts came out of the dramatic portions. Many of the actors listed in the cast may not be seen in the 121-minute cut version which Turner Classic Movies (TCM) has shown.
Vidor had originally thought he had an understanding with MGM that Spencer Tracy and Ingrid Bergman would play the leads.
Louis Adamic, author of memoirs and studies of the immigrant experience, drafted the first sections of the script.