Visible crew/equipment: When the Animal Control guy and the officer are in the grocery store, a few shots after the tiger jumps over the counter, the hand of a crew member (presumably the tiger's trainer) is visible behind the boxes holding a piece of food, as the tiger walks toward it (away from the camera).
Camera Bug - S4-E10
Visible crew/equipment: After Johnny snaps the picture of Marco on the engine, when he prods Chet to go stand by the map, as the camera moves to the left we can see the reflection of production equipment/crew on the back of the squad, and we can even make out the shape of someone seated on a director's chair.
Camera Bug - S4-E10
Visible crew/equipment: When the stretcher with the unconscious teenager from the school fire is wheeled into the ER, while Roy is using the Ambu bag, just before they reach treatment 3 we can see the top of the set down the hall, near the nurses' station.
Daisy's Pick Blind Date - S4-E7
Visible crew/equipment: After Brackett's examination of Jerry, the unconscious 3 year old, when he goes to the waiting room and introduces himself to Jerry's parents, the top of set can be seen over treatment 1.
It's How You Play the Game - S4-E19
Visible crew/equipment: When Johnny walks into the kitchen and gets the cold shoulder from Marco and Mike, and then when Chet walks in, the reflection of production equipment is visible on the oven's glass.
It's How You Play the Game - S4-E19
Visible crew/equipment: After Mike and Marco ignore Johnny as he walks into the kitchen, when Roy holds the chrome coffee pot and pours Johnny a cup of coffee, the reflections of the camera/lights are visible on the coffee pot's chrome surface.
Visible crew/equipment: When Brackett, Early, and Morton enter treatment 1 to examine the hallucinating veteran, inside there's a young doctor standing to the left of the door. After Brackett tells Morton he wants an EEG, skull x-rays, and brain scan, when Morton heads to the phone to order the neurological workup, we can see the actor's white tape mark under the gurney, where the young doctor had been standing.
Visible crew/equipment: After the ambulance arrives at the lion pit, just as the attendants reach the fence where John and Roy are standing, and the stokes is loaded onto the stretcher, we can see the two white tape marks on the ground, where the zoo employee is standing.
Visible crew/equipment: When we hear Station 51 being dispatched to the structure fire at Kiddytime Toy Factory, just as Roy rushes to the squad's door to open it, we can see the reflection of the camera dolly through the squad's windshield as it moves.
Visible crew/equipment: When the doctor shows up at the house of the man who kicked in his TV, as the camera moves back, the top of equipment (presumably the boom mic) is visible and moving in the reflection of the mirror on the wall.
Visible crew/equipment: When Johnny and Roy are working on the man who is unconscious due to electric shock, the bulging outlines of the lavalier mic transmitter and wire are visible on the back left side of Johnny's shirt.
Visible crew/equipment: When Roy and Johnny are at the laundromat with the drunk man, the bulging outline of the mic transmitter is visible on the left side of Johnny's shirt, over his belt.
Visible crew/equipment: When Charlie, who has smoke inhalation, is placed on the gurney in the treatment room, the actor's white tape mark is visible on the floor, where the nurse stands in a moment.
Camera Bug - S4-E10
Visible crew/equipment: At the accident scene with the truck carrying dynamite, when Roy is leaning over the driver's door, the outline of the mic transmitter is visible on the back, right side of his shirt. Then, when they're carrying the driver to the top, Johnny's becomes visible at his left side.
Camera Bug - S4-E10
Visible crew/equipment: When Johnny is driving Roy nuts by taking closeup pictures of him checking the squad's engine, the outline of the lavalier mic wire is visible on Johnny's back.
Camera Bug - S4-E10
Visible crew/equipment: At the school fire, when Johnny is administering the O2 to the teenager with smoke inhalation, the bulging outlines of the mic transmitter and wire are visible on the back, left side of Johnny's shirt.
Visible crew/equipment: When all the guys are talking to Mr. Gibson, who is stuck in the trench he fell into, the outlines of the lav mic transmitters are visible on the backs of Roy's and Johnny's shirts.
It's How You Play the Game - S4-E19
Visible crew/equipment: When Roy and Johnny are on scene at the car accident, the bulging outlines of their mic transmitters and wires are visible on the left sides (above the belts) of their shirts.
Visible crew/equipment: When Johnny and Roy are at the home of the pregnant woman who was shot, the bulging outline of the mic transmitter is visible on the back, left side of Johnny's shirt.
Daisy's Pick Blind Date - S4-E7
Visible crew/equipment: When the unconscious little boy is loaded into the ambulance, we see the actors' chalk x marks on the ground, where Roy, the boy's father, and mother are all standing.
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.