Screenwriter Mary C. McCall Jr. said that the script was based mostly on the life of William Boyd, who had long played Hopalong Cassidy and for whom her husband (and co-writer) had worked in the 1930s: "It was a case of the man becoming the part - with the passage of time, Bill Boyd and Hopalong Cassidy were indistinguishable one from the other."
About two months before this film was released, the Perry Mason (1957) series began its nine-year run on the CBS TV network. Many of the film's cast members are connected with the series. Barbara Hale and William Hopper were regulars for the entire run of the series, she as Mason's confidential secretary Della Street and he as private investigator Paul Drake. Bill Williams, who was Hale's real-life husband for 46 years until his death in 1992, was in four episodes of the series. Julie Adams also appeared in the series four times, including in The Case of the Deadly Verdict (1963) where she was the only one of Mason's clients to be convicted of murder. Appearing twice were Joanna Moore, Maggie Mahoney, Walter Reed, Roxanne Arlen. Ben Johnson made one appearance.
Both Julie Adams and Joanna Moore played nurses on The Andy Griffith Show.