According to Ed Lauter, the casting director refused to see him for the role of Galloway. Lauter made a plea to George C. Scott, who then demanded that Lauter be cast.
According to "Halliwell's Film Guide", this movie "spawned the television series Sulle strade della California (1973) and Pepper Anderson agente speciale (1974)".
According to Stacy Keach, the studio initially opposed having his white character falling in love with a black woman, preferring a Hispanic or mulatto woman instead.
Apparently, Columbia Pictures paid Joseph Wambaugh, who wrote the novel on which this film was based, a bonus of $1250 for each week his novel stayed on "The New York Times" best-seller list. The novel debuted on the list on February 21, 1971, and stayed on it for 32 weeks, thereby earning Wambaugh a total bonus of $40,000.
This movie was re-titled "Precinct 45: Los Angeles Police" for its British release.