When Druggin was looking at the index cards of the prisoners, a close-up shot on Hansen's card shows an entry for Bertillion (sic) Measurements. The Bertillon System was created in the late 1800s by Alphonse Bertillon, a French police officer and biometrics researcher, who applied the anthropological technique of anthropometry to create a human identification system based on physical measurements. Anthropometry was the first scientific system used by law enforcement to identify criminals. Before that time, criminals could only be identified by name or photograph. The Bertillon System consisted of five measurements: head length, head breadth, length of middle finger, length of the left foot, and length of the cubit. Along with these measurements, Bertillon set a standard for facial photography, now known as the mugshot, to complete this system. Although the system was based on scientific measurements, it was known to have its problems. For example, it did not work accurately with women or children because it was based on the data of men who had reached full physical maturity and had short hair. The Bertillon System was eventually replaced by fingerprinting.
The trailer presently being offered on the IMDb website is from the 1948 re-release, in which the billing positions of O'Brien, originally billed first, and Bogart, originally billed third, have been reversed so that Bogart now gets top billing.
The convict who likes "I'm Forever Blowing Bubbles" might do so because it is the song associated with Jimmy Cagney in Der öffentliche Feind (1931), one of the first great gangster movies.
The steamroller parked as part of the roadblock to end the road-gang escape attempt bears a plate saying it's made by The Buffalo Springfield Roller Co. of Springfield, OH. The legendary sixties rock group took their name from seeing such a steamroller parked outside their managers' office.