Continuity mistake: The window from which the sniper is firing sustains damage with broken glass panes, but then the glass panes are whole and intact, and then they are broken again.
Continuity mistake: When Johnny and Roy are treating the officer, while hiding between the bakery truck and car, the sniper fires at them which leaves multiple bullet holes on the side of the truck. However, when Vince talks to the Sergeant on the handie-talkie and then fires the tear gas, all the bullet holes on the truck are gone, but they soon reappear.
Visible crew/equipment: After the sniper surrenders, Captain Stanley instructs Engines 12 and 51 to come to the rear of the building, and a few shots later the camera moves alongside Engine 12 as it's turning the corner. In this specific shot, up ahead we are able to see set lighting (including moleeno-style array lights), equipment, crew and actors (in the blue paramedic uniforms), some sitting on chairs in front of the parking attendant's booth (which was shot at by the sniper during the scene).
Answer: I believe you are speaking of the old man, Mr. Wilson. He's played by J. Pat O'Malley.
Bishop73
Correct, it was J. Pat O'Malley...he also played the grandfather with his grandson when their rocket exploded, and also played "Old Bill" in the episode with Ann Prentiss, where Gage saves the little girl from the burning tree house, and her mother falls in love with him.