Was the Grapefruit scene ad-libbed?
According to one Hollywood rumour, the script actually called for Cagney to back-hand Mae Clarke in the face, but Cagney didn't have the heart to even pretend to slug a woman. So at the crucial moment he went for the grapefruit instead.
Which worked out well in the end anyway. It created a classic moment.
After all there were plenty of gangster movies in the day showing a woman getting manhandled.
But how many of them show a grapefruit getting shoved in her face?