Wissenswertes

Underworld settings in the USA featured in the movie included Skid Row in Los Angeles and Little Italy and Spanish Harlem in New York City.

The unsettling poster Bronson's character has in his apartment is a detail from "Saturn Devouring His Son" a painting by Spanish artist Francisco Goya.

In the novel, the main character is called Derek Torry, not Lou, and the entire story is set in the UK.

In his autobiography, "Winner Takes All: A Life of Sorts," director Michael Winner explained that often Charles Bronson would forget his reading glasses at the set and when he and Bronson went out to lunch at a restaurant, Winner would have to read the menu to Bronson.

The name of the reclusive hippie monastic religious commune in Carmel in California, USA was the "Ashram of the Circulating Light".