Continuity mistake: When Roy, John, and Marco walk into the rec room while Chet is trying to wax the floor, Marco is wearing a ring on his left hand in the wide shots, but in the closeups with Captain Stanley the ring is gone.
Continuity mistake: At the gas station, when Captain Stanley asks Marco to open the gas pump and close the shut-off valve, Marco is wearing two rings - one on each of his ring fingers, but when he is nearly electrocuted both rings have vanished.
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.