The film was shot in Mexico under great secrecy by Hollywood's standards, as its subject matter was considered so controversial.
Nathaniel Davis, who was the U.S. Ambassador portrayed in the film (played by actor Richard Venture), went on to file a $150 million libel suit against Universal Pictures and Costa-Gavras after the film was released. It was eventually dismissed. In a January 2007 Q & A with Costa-Gavras about the film, the director credited this to Lew Wasserman, then head of Universal, who so strongly supported the film that he insisted the studio absolutely refuse to negotiate any kind of financial settlement whatsoever.
Ed Horman and Joyce Horman ("Beth" in the film) worked very closely with Costa-Gavras, Lemmon, and Spacek throughout the film's production. Costa-Gavras said that after Pinochet died (in December 2006), both he and Joyce Horman felt regret that the former Chilean dictator was not brought to justice.
Years after the film's release, with the advent of advanced DNA testing, it was determined that the body shipped back to the United States (as seen in the film's final image) was NOT that of Charles Horman. Joyce Horman actively continues to search for the truth behind her husband's capture and murder.