Filming took place in Brighton using hidden cameras amongst the real-life crowds. This was mainly because the Brighton authorities objected to the way their town was being depicted as a haven for gangsters.
Brighton Borough Council refused permission for use of the race course because of the damage association with gang crime would do to the town's image. (See the on-screen disclaimer at the start of the movie.)
Sir Richard Attenborough reprised his role from the stage version three years earlier. Hermione Baddeley and William Hartnell had also appeared in the theatrical production.
Writer Graham Greene wrote Sir Richard Attenborough a letter after seeing the movie, praising his performance as Pinkie. Attenborough kept the letter for the rest of his life.
"You are Kolley Kibber, and I claim the Daily Messenger prize." This was paraphrasing The News Chronicle, which had a promotional character called "Lobby Ludd", who toured seaside towns giving away five pound notes after being successfully challenged.