While walking the streets of Seattle in the movie, James Caan is approached by a panhandler who asks him for change. The man was an actual panhandler who didn't see the cameras on the street, and mistook Caan for a real sailor.
"Cinderella Liberty" is Navy slang for temporary absence from ship or station, which ends at midnight on the last day. Typical periods of liberty are twenty-four to seventy-two hours.
According to Glenn Erickson's review for the Trailers from Hell website, the U.S. Navy refused to co-operate with production because the film depicts desertion of duty with no consequences, so Twentieth Century Fox had to rent a Canadian ship.
According to an article in the June 6, 1973 edition of Variety, the U.S. Navy originally planned to assist in this production, but pulled out, objecting to the portrayal of sailors in bars cavorting with "fleet chicks".
Darryl Ponicsan wrote the screenplay to this film, adapting his own novel. Another of his novels, The Last Detail (1973), also about Navy life, was also made into a film in 1973 and that screenplay was adapted by Robert Towne. Towne was nominated for an Oscar, but Ponicsan was not despite an excellent screenplay for Cinderella Liberty (1973) and providing the source material for both films.