When Donald passes the mailbox, the mailbox flag starts waving like a telegraph key, sounding out Morse code. The code translates to 'CQ HI KID'. In amateur radio protocol, CQ means 'Calling all stations', a general call. The code is -.-. --.- .... .. -.- .. -..
The voice of Donald's Angel was provided by Thelma Boardman in her first voice acting role for Disney. She would then go on to voice Minnie Mouse for a few years.
The voice of Donald's Devil was provided by Don Brodie in his first voice acting role for Disney. He would then go on to voice the Carnival barker in "Pinocchio.