The Flying Serpent is what I have read to be a "rehash" of Devil Bat, substituting George Zucco for Bela Lugosi. There are similarities that I found while watching it at http://www.archive.org/details/THEFLYINGSERPENT1945_5.
However, I kept thinking of The Feathered Serpent while watching it. I expected the Chans and Birmingham Brown to show up.
This is what I found at http://www.imdb.com/title/tt0038531/plotsummary:
The demented archaeologist Dr. Andrew Forbes (George Zucco) discovers a living, breathing serpent creature known to the Aztecs as Quetzalcoatl (the Killer Bird God) and accidentally kills his wife by giving her one of the beast's feathers, causing the creature to track her down and slaughter her. Now Dr. Forbes uses this twisted knowledge to extract revenge upon his enemies by placing one of the serpent's feathers on his intended victim and letting the beast loose to wreak havoc.
