Based on the true story of Emerich Juettner, an elderly junk dealer who, like the character in the movie, only used to print counterfeit $1 bills to make ends meet. For 10 years, Juettner eluded the Secret Service's efforts to find him. He was finally caught in January, 1948, after a fire forced him to vacate his apartment on New York's Upper West Side, and move in with his daughter in Queens. The firemen who put out the fire left some of Juettner's belongings in a nearby alley. A few weeks later, a group of local boys found some of his $1 bills in the alley, realized they were fakes (the name "Washington" was misspelled as "Wahsington" on the bills), and turned them over to police. Juettner was arrested, but only sentenced to nine months in jail and a $1 fine. When 20th Century Fox bought the movie rights to his story, Juettner received more money than he had ever made as a counterfeiter.
The Oscar-winning 1946 song "Mam'selle", which is heard as Steve and Ann enter the nightclub, was written by director Edmund Goulding for his film version of Le fil du rasoir (1946). It also was used later in Pickup on South Street (1953).
The misspelled "Wahsington" on the bills (based on fact) is perhaps not quite as inept as it may seem at first glance. The bills were printed from photo-etched plates, which required some hand touch-ups. Looking directly at them, one sees a mirror image of the printed bill - "notgnihsaW" (but also with each letter itself reversed).
"Lux Radio Theater" broadcast a 60-minute radio adaptation of the movie on October 15, 1951 with Edmund Gwenn reprising his film role.