While in Germany before the war, director Douglas Sirk met Reinhard Heydrich at a party, and later recalled that "he made my blood run cold."
Although this film was originally filmed by poverty-row studio Producers Releasing Corp. (PRC), the word got out in Hollywood that the picture was far and away the best thing PRC had ever done; MGM executives got a look at it - including Louis B. Mayer, were suitably impressed, bought it from PRC, added a few scenes for increased dramatic effect, and it was released as an MGM picture.
The footage with Ava Gardner, Frances Rafferty and Leatrice Joy Gilbert was shot by MGM and inserted into the film after it was purchased from PRC.
This film shows the men of Lidice being machine gunned in the town square. In fact, the men were marched to a nearby farm and shot in groups of five, then ten against the barn's stone wall. This took from early morning to mid-afternoon. Most of the women were sent to Ravensbruk concentration camp in Germany. Most of the children, save for a few selected for "Germanization" were sent to the Chelmno extermination camp in Poland and gassed.
Reinhard Heydrich was not shot by a machine gun on a country dirt road as depicted in this film, but was mortally wounded by a modified British anti-tank grenade on a Prague city street in the 8th District near Bulovka Hospital. This occurred on May 27, 1942. Heydrich died of sepsis on June 4th at that hospital.