The story goes Buster accidentally missed the second building, which necessitated devising him falling through window awnings and swinging on rainspouts to salvage the 'failed' scene.
I believe the fall we see onscreen was planned that way all along. Does Buster’s body language reveal the startled shock of an accident victim desperately grabbing for the ledge? Or someone calmly falling into a net as planned?
What do you think? You can see more clues, analysis, and images on my blog.
https://silentlocations.com/2025/05/22/buster-keatons-three-ages-leap-of-faith/
From my blog you can download a very detailed PDF article about this as published in The Keaton Chronicle