Although Charlie Chan's daughters appeared with him in previous films (including Charlie Chan em Honolulu (1938) and Charlie Chan no Circo (1936)), this is the only film in which a daughter (Frances) plays the assistant role usually filled by one of Chan's sons (Lee, Jimmy or Tommy).
The title card on the DVD, which comes from the original negative, bears the original title, "Black Magic", but revisionists have superimposed "original title: 'Meeting at Midnight'" across the bottom of the screen. They've got it backwards. "Meeting at Midnight" was the new title attached to the film, about five years after its original release, in order to avoid confusion with Orson Welles' "Memórias de um Médico (1949)."
This was the second time that Frances Chan played Charlie Chan's daughter. A decade earlier, she played Charlie's youngest daughter in "Charlie Chan's Greatest Case" (1933). It is unclear if this was supposed to be the same character grown up.
Actress Frances Chan didn't have to stretch too far in this role. She played a character named Frances Chan.
The 33rd of 47 Charlie Chan movies.