The federal Volstead Act did not prohibit drinking alcohol. It prohibited manufacture, sale, transport, distribution and import/export.
It was left to the states to make laws to prohibit possession and consumption. All the states did, but Nevada's was repealed on state constitutional grounds.
Elmore Leonard said that one day while he was on set watching a scene being shot, Patrick McGoohan came up to him and said "What's it like to stand there and hear your dialogue all fucked up?"
The September 3, 1969, issue of VARIETY reports that Claude Johnson took over the small role of "young man" from actor Ted Barnum (credited as Charles Akins) when Barnum declined to do the nudity required for the role.
Location scenes filmed in Stockton, California.
The song which plays in the background as Frank Long registers at the hotel is 'You Are My Lucky Star' from the musical Broadway Melody of 1936 (written in 1935). Prohibition officially began in 1920 and ended in 1933.