Graham Greene, on whose novel the movie is based, said that it was "the only good film ever made from one of my books by an American director."
Franz Waxman re-used his title music for this movie in Dark Passage (1947). The same music was also used over the titles in To Have and Have Not (1944).
At the end of the movie, Charles Boyer says that the fighting will end and the world go back to normal some day. Many movies made during and after World War II ended like this, with viewers comforted by knowing or being confident that peace would come soon. However, this movie is about the Spanish Civil War, which was won by the Fascist side and, with no intervention from other countries, they remained in power for another thirty years.
Reviews were so disastrous that Warner Brothers decided to add extra scenes with Humphrey Bogart and Lauren Bacall to The Big Sleep (1946) in order to build up her role and hopefully limit the damage to her image.
The "Entrenationo" language school may be a reference to Esperanto, a constructed language invented in the 1870s-'80s to foster communication and harmony between people of different nationalities. Esperanto speakers came under suspicion in such right-wing or Fascist countries as Nazi Germany (because the inventor was Jewish), Imperial Japan and Francisco Franco's Spain.