When Nipper Read assembles his task force to go after the firm,in the background on the wall are mugshots of Jack 'The Hat' McVitie, Frank Mitchell, and George Cornell. At this point Jack was still alive, and thus his picture shouldn't have been up there alongside the other murder victims.
When Ronnie shoots Cornell in The Blind Beggar, he appears to look at his own reflection in the pool of blood on the floor in front of him. It would be impossible for him to see himself in a reflective surface at that angle.