The scene when Regal first goes inside a building to visit his mother was filmed on Second Street in Los Angeles, California in what is called Little Tokyo.
When Phil and Rosalie are talking on the roof of their building, there is a billboard for Frankel. Max Frankel is the Art Director for for the film.
The sign says Frankel and Black. Ralph E. Black was the Production Manager.
Lee Van Cleef has an uncredited role as the jewel fence Harry Goldish playing in the fixed poker game with Nicky Bradna. Van Cleef had begun his feature film career in 1952. He went on to bigger roles in westerns High Noon and For a Few Dollars More. He died in 1989 at age 64 of a heart attack.
The billboard where McFarland is beaten by Regal's hoods advertised highway safety and contained a cross inside a circle. That is the "Green Cross for Safety" logo of the National Safety Council, a non-profit group that advocates for highway, workplace, and community safety in the United States. Ironically, the roadside billboard reads "Drive Carefully--The life you save may be your own."
Nicky's $95.00 per week salary on this 1955 film translates to about $1,050 per week in 2022 dollars.