The film was shot on the same set that was the McBain ranch from Sergio Leone's Once Upon A Time In The West. In that movie the railroad was supposed to run through the ranch because there was a well on the property. At one point in this movie Bud Spencer even says, 'so this is the famous well.'
The prostitute Coburn goes to see is called La Vedova Warren. George Bernard Shaw, the Irish playwright wrote a famous play about a prostitute called Mrs Warren's Profession.