Scarlet Street : 'ghost smoke'?

In the end (1 hr 38 minutes in), Christopher is quite mad and walking down the sidewalk, just before he comes face to face with the painting of Kitty a man overtakes him on the sidewalk and a puff of "smoke" seems to come from behind Christopher. I just wonder if that was on purpose - it was brilliant if it was. It was almost as if Kitty's ghost came from behind him and raced in front to be there when he comes face to face with her painting. Then he hears her voice again. You have to have a good copy of it to see it.

Thanks, I just checked it!
Good observation

Yes, I saw that too. Hard to tell as to whether it was planned or just a stroke of luck. I think it may have been cigar smoke from a passerby. Beautifully filmed that scene, I bet the cameraman's heart pounded a little faster when he realized what a great shot he had captured.

He was on Planet Earth the whole time!