Other mistake: At the start of this episode the tones drop and Station 51 is dispatched to a fire and explosion. In this closeup, all the guys come running from the kitchen into the apparatus bay and head for the vehicles, but wait, none of them are actually 51's guys.
Other mistake: When Roy and Johnny are with the guy who somersaulted off the roof into the pool, Johnny is in the pool giving him oxygen, and in the closeups Johnny's left hand varies between very hairy, not hairy at all, normal fingernails and bitten up fingernails. Additionally, the hand holding the mask on the boy's face changes back and forth between Johnny's left and right hand, between shots.
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.