 Edward Woods was originally cast in the lead role of Tom Powers and James Cagney was cast as Tom's best friend Matt Doyle, until director Wellman decided Cagney would be more effective in the part and switched the two actors but never reshot the sequences with the characters as children, which is why the child playing Cagney's role looks like Woods while the one playing Woods' role looks like Cagney.Another reason for the switch is that the sound technology used in "The Public Enemy" was superior to that used in earlier films, making it no longer imperative to have an actor in the lead role who had impeccable enunciation.Louise Brooks was the original choice for Gwen Allen, a woman with self-confessed weakness for bad men.