Other mistake: During the structure fire, when Engine 98 rolls up we can see the large red vinyl adhered to the top of the engine's cab. Then, when Truck 106 rolls up we see its company number 106 on the door, but in the overhead shot we can see the number 8 on the roof of the cab, not 106. This presumably means that the door has one of the prop dept's magnetic decals imprinted with 106, and the roof still shows the Truck company's real number.
Other mistake: After finding out about Valerie's three kids, when Johnny and Roy are sitting in the station's locker room at the start of their next shift, there are a few moments during this conversation where Kevin Tighe softly mouths some of Randolph Mantooth's lines as Johnny is speaking, particularly when Johnny says "Beautiful chic."
Other mistake: After Station 51 is dispatched to the structure fire, just as Roy and Johnny start heading upstairs we see footage from 4x3, "Gossip," when Johnny brings the hose to the stairs at the chemical fire, but the line doesn't reach so he leaves the hose at the bottom step, and they continue up.
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.