Trivia: Doyle Lonnegan's limp was a result of Robert Shaw injuring his ankle. Rather than working around it, Shaw incorporated the limp into his performance.
Trivia: Producer Julia Phillips (died 2002) became the first female producer to win an Oscar for "Best Picture" for this film. The Oscar for "Best Picture" goes to the producers of the winning film since 1952. She shares the Oscar with fellow producers Tony Bill, and her then-husband Michael Phillips.
Trivia: Even though it sets the mood for the film, Scott Joplin's ragtime music was no longer popular during the 1930s.
Trivia: Although the movie was released in 1973, Robert Redford didn't actually see it until 2004, on the suggestion of his grandson.
Chosen answer: Snyder only knew that Erie was friends with Hooker, and he wasn't on Lonnegan's payroll, just a run-of-the-mill corrupt policeman, so he didn't know Erie was involved. The Courier barely saw Erie and so may not have been able to identify him as well as he did Hooker and Luther, so Erie was unknown to Lonnegan.