Other mistake: When the squad and engine roll up on the scene of the bulldozer accident in the junkyard, just as the guy runs up to inform them about the victims, have a look at Squad 51's license plate number because it is not the normal prop plate number E999007.
Other mistake: After Johnny gets hit by the phantom in the apparatus bay, Station 51 is dispatched to an unknown type rescue at 617-1/2 Kimball Rd, and before the dispatcher even gives the address, Mike has already located the area on the map with his finger.
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.