O Mistério do Rádio

Sidney Toler

Charlie Chan

Benson Fong

Tommy Chan

Mantan Moreland

Birmingham Brown, Chauffeur

Robert Homans

Capt. Flynn

I. Stanford Jolley

Rolf Brot, alias Ralph Brett

Virginia Brissac

Mrs. Marsh

Jack Norton

Willie Rand

Janet Shaw

Gloria Bayne

Ben Carter

Ben Carter

Victoria Faust

Hulda Swenson / Janet Carter

Helen Deverell

Diane Hall

Leonard Mudie

Horace Karloss

Reid Kilpatrick

Mr. Chester, program announcer

Emmett Vogan

Mr. Hamilton

Crane Whitley

Henchman Cooper

Kernan Cripps

Detective (uncredited)