Visible crew/equipment: When Roy and Johnny pull into the parking space near the car with the toddler inside, as the camera moves we see its moving reflection on the side of the car. Then when the woman says "Certainly something's wrong with him, he's unconscious," as the camera pulls back we can see its reflection in the car window. We can also see the reflection of the large location lighting when Johnny tries to unlock the door with a wire hanger.
Other mistake: When Johnny and Roy are with the baby who's sleeping in the back seat of the locked car John says, "The roof is hot, I think the heat might have built up inside," and the bystander says, "Lord knows how long he's been lying in there broiling in the sun," but what's funny is that they're all wearing winter coats and jackets.
Revealing mistake: At the construction accident with the trapped man, when Engine 34 rolls up on scene we can see the red vinyl material adhered to the front of the engine, covering its real company number.
Audio problem: After Johnny successfully unlocks the car with the toddler inside, when he and Roy hold him the audio we hear is of the toddler crying, even though in some shots it's obvious that he's not really crying. Additionally, when the toddler was still locked in the car wrapped in a blanket, in the closeup his hair (actually a doll's hair) is much thicker and longer than it is when they get him out.
Continuity mistake: When Station 51 is dispatched to the man trapped at the construction site, there are closeups of the shaky concrete wall that may collapse before they shore it up with 4x4 support beams, but in following closeups of the same angle those support beams they added have vanished, then they reappear.
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.