Visible crew/equipment: After Johnny cuts the cable holding Lorenzo's locker, when Johnny climbs down the outlines of the mic transmitter and wire are visible on the back of his shirt.
Other mistake: During the surgery on Brackett's father, after the closeup of the anesthesiologist there is a closeup of the Bird's Mark 4 unit, then a closeup of the bellows housing showing inflation and deflation, but on the bellows unit it reads "Animal Anesthesia Ventilator" made by Bird.
Continuity mistake: When Chet and Marco are hosing the gas meter fire, they are both wearing gloves while handling the hoses. However, after Roy helps Chet up from his stumble, there is a closeup of the hoses and it's a bare hand handling the hose.
Continuity mistake: Just after Brackett tells Early that the patient he was talking to is his father, it cuts to a shot of Squad 51 pulling up the driveway, and the Engine 51 we see parked in the apparatus bay is not the current Ward LaFrance pumper, it's the original Crown engine from seasons 1 and 2.
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.