Continuity mistake: When 51's guys are on the roof of the jail, Johnny sets up the red hose roller with a safety line on the roof edge between the two ladders, but when Roy climbs up the orange ladder to go over the edge, that hose roller with the safety line are not on the roof edge and can be seen still lying on the ground, then it reappears in place in the aerial shot. Additionally, when Roy goes over the roof to make his descent, there's a second silver hose roller at the base of the overhang, which was never actually placed there.
Continuity mistake: When Squad 51 is dispatched to the possible heart attack, the address given is 11044 Conquistador, but when they arrive at the incident the addresses on the homes are 8042 and 8046.
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.