This nifty little film from the late 30s begins with an odd logo:
But I can't find the B. I can find all the letters except the B. Anyway:
You sense it's not the most serious movie ever done, based on the call letters of the radio station:
Since it's one of those talky mysteries where everyone runs from room to room saying things, the sets aren't too remarkable - except for the opening scenes in the radio station's skyscraper HQ. Wow:
I've no idea where it is. And for God's Sake, LOOK at this elevator indicator:
One old actor stuck out: he plays a hearty ethnic cliche of the day, the Humble Italian Janitor, Tony:
You may think: do I know him? Perhaps. Let's-a listen to-a his-a talking, eh?
Does that narrow it down for you? If so, you share the same emotion I had: time travel. That's the only explanation. He went back when he got older and did old-guy movies in the past to amuse himself. I had to check imdb to see if his body was ever found; it was.