Visible crew/equipment: In the locker room, after Chet tells Johnny that he knew all about the practical joke, when they walk to the door together there's a quick glimpse of the cameraman's reflection on the door's glass, before John tells Chet about the fictitious five dollar bill down by Mike's locker.
Visible crew/equipment: When Roy and John get back to the station, and Marco walks up to the squad to talk to the guys about the practical joke they're going to play on Chet, on the squad's spotlight we can see the reflection of the camera, which is in front of the map.
Visible crew/equipment: When Brackett walks out of his office, Betty walks over to him and asks if it's okay to go to Dixie for help with the nurses' scheduling problem, and the bulging outline of the mic transmitter is visible on the back of her uniform, directly under its zipper.
Visible crew/equipment: When deciding how to rescue Cora from the middle of the cactus patch, Mike parks Engine 51 at the side of the road, beside the hill with the cactus. During the rescue there are closeups of Cora's husband standing beside Engine 51, and we see other things reflected on the engine instead of just the side of the hill. Additionally, his position in the closeups differs from where he stands in the wideshots.
Visible crew/equipment: When the guys are at the scene of the vehicle accident, after Roy asks Captain Stanley and Captain of 69 to assist the man to the top of the hill, the reflection of the array lighting is visible on the side of Engine 51 as Mike works the engine's pump panel.
Visible crew/equipment: At the structure fire at an abandoned building, when Engine 164 arrives, we can see the reflection of the location's array lighting in the driver's side window.
Visible crew/equipment: After Johnny reads the note from Mr. Laurents, which he left with the package of money in the fridge, Captain Stanley walks over to the counter, where the actor's T-mark is visible on the floor.
Visible crew/equipment: At The Game, when Roy and John respond to the possible heart attack which turns out to be a hyperventilating man, his wife stands behind Roy, and the bulging outline of the lavalier mic transmitter is visible on the back of her yellow blouse.
The Girl on the Balance Beam - S5-E18
Visible crew/equipment: While en route to the woman trapped on a wire, the reflection of the cameraman is visible on the windshield after Mike drives past the entrance to Commercial Studios. We see it's not Captain Stanley, but instead it's someone wearing a white shirt, holding up something (presumably the camera) with both hands.
The Girl on the Balance Beam - S5-E18
Visible crew/equipment: At the gym, when Nancy wants to prove that she's feeling fine, she tries to do a cartwheel, and the outlines of the mic transmitter and wire are visible on the back of her leotard.
Visible crew/equipment: When Chet is trying unsuccessfully to get Henry to use the dog house, the outline of the mic transmitter is visible on Chet's back.
An Ounce of Prevention - S6-E13
Visible crew/equipment: When Station 51 is dispatched to the man who's ill on the ferris wheel, just as Engine 51 rolls out of the apparatus bay, in the closeup we see the reflection of the array lighting and the reflector screen on the side of the engine.
Visible crew/equipment: When Charlie stops at the station to service Engine 51, while Roy and John are trying to service the squad, the multiple reflections of location array lighting are visible on Charlie's squad, and on Squad 51's spotlight.
Family Ties - S6-E16
Visible crew/equipment: At the house fire, when Chet finds the teenagers in the attic, just after Marco climbs in through the window, we can see the moving shadow of filming equipment (looks like the boom) by the stool.
Visible crew/equipment: When 51's guys are at their practice game, the gymnast is injured and the outline of the mic transmitter is visible on the back of Johnny's T-shirt. (00:16:40)
Visible crew/equipment: While Roy's in the office making out the activity report for the training center, Johnny walks over to Ed who is standing beside the map, and when they're dispatched to the overdose, as they get into the squad we can see two tape marks (one white, one black) on the floor, where Johnny and Ed had been standing.
Visible crew/equipment: After Chet gives Johnny the idea about the TV show, when Chet stands up to leave the kitchen the top of the set is visible at the right corner.
Visible crew/equipment: When Roy walks into the ER with the actor who plays Dr. Ned, the nurse rushes over to Roy, and when she asks him about the actor, we can see the bulge of the lavalier mic transmitter at the back of her uniform.
Visible crew/equipment: When Johnny and Roy are with the man whose fingers are caught in the chain of the garage door opener, just as the man's wife sticks her head out the door to direct 86 to the garage, the outline of the mic transmitter is visible on the back of her blouse.
Visible crew/equipment: At the studio, before John tests Wally's equipment, when Roy says that he's going to get their equipment from the squad, Johnny rushes after him and we see the reflection of the camera crane and array lighting facing Squad 51.
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.