A scene where Quinn first goes inside a building to visit his mother, that street was filmed on Second Street in Los Angeles, California in what is called "Little Tokyo".
As Phil Regal (Anthony Quinn) loses his grip and plunges to his doom, he's first replaced by a stuntman, and then by a mannequin with a shiny, painted head that doesn't even match Quinn's dark hair color.
In the final scene, Phil Regal (Anthony Quinn) hides behind a brick wall on the rooftop while police shoot at him. Bullets ricochet off the wall right by his head; but from where the police are standing, it would be physically impossible for their bullets to hit that spot.