female onlooker

There's a scene about 45 minutes into the film where Marcus and Carlo are talking together in a large public area, some sort of arcade, and while we see them close to a wall to the right, medium shot, in the left far background there's a woman smoking a cigarette and peering in their (or our) direction. The scene seems to be framed by the camera for us to notice her, as if she's significant. Is she? Is she supposed to be one of the characters, or just an extra who couldn't resist looking at the camera, or what?

"I beseech ye in the bowels of Christ, think that ye may be mistaken."