In his second autobiography "Images: My Life in Film", Ingmar Bergman describes the filming of the exteriors as his actual film directorial debut: "When the film was virtually done, I made my debut as a movie director...[the] final scene shows Kjellin in the light of dawn, walking towards the awakening city. I was told to shoot these last exteriors, since Sjöberg was otherwise engaged. They were my first professionally filmed images. I was more excited that I can describe."
The Latin teacher Caligula is based on the Latin teacher Sjögren in Hasse Ekman's Lågor i dunklet (1942), also played by Stig Järrel.
The daily news paper Caligula reads while visiting Bertha is the Nazi newspaper "Dagsposten".