Continuity mistake: When Engine 51 gets the run in the middle of the night, the engine company rushes to the rig including Johnny, which leaves Roy standing in the dorm alone. After he shouts out to Johnny from the doorway, when Roy turns to go back into the dorm, some changes have occurred - the locker room door is now closed, there are clothes lying on Cap's bed where none were a moment ago, etc.
Continuity mistake: When Engine 51 gets the run in the middle of the night, Johnny's so tired that he stands on Engine 51's tailboard half asleep, and as it rolls out of the bay and makes a right turn, Roy shouts out to him that the run is not for them. There are two problems with this. The entire back of Engine 51 is different between the closeup and wide shot - the surface, the lights, the license plate area, etc. Also, the engine makes a right turn out of the bay, but Roy's looking out towards the left while he's shouting, as if the engine's turning left.
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.