I think I read it in this film's details that, near the film's start, a man in the street suddenly vanishes mid-frame?
I'm not sure if it's a CGI man, but I keep missing it in my version (ordinary dvd R2 cut) or the Fanedit version?
The beginning of the film is an opium dream that Abberline is having, so it makes sense that a man would vanish as its an opium dream.
Another explanation is the use of blue/green screen by the filmmaker to extend the set. If an actor had to avoid walking into the screen he/she may have stepped aside or turned around and in the editing of the film this was noticed and digitally corrected.