Visible crew/equipment: When Roy and Johnny are with the boy who bit the dog, as they kneel down to get the hiding dog, the outlines of the mic transmitter and wire are visible on the right side of Johnny's shirt.
Visible crew/equipment: On scene at the fire caused by gasoline stored near a boiler, when Johnny and Roy are with the burn victim, the outlines of the lav mic transmitter and wire are visible on the back, left side of Johnny's shirt.
Visible crew/equipment: After Valerie is hit by the car, when Roy and Johnny tend to her, the outlines of the mic transmitter and wire are visible on the back, right side of Roy's shirt.
Visible crew/equipment: During the structure fire, after Roy and John climb out onto the ledge and the fire flashes in the exterior shots, the next interior shots we see shows stacked boxes falling as the fire flashes through the doors. The interior shots are from episode 3x7, "Promotion", during the structure fire, after the security guard is taken down the ladder. We can even see a crew member's hand pushing a lower box which causes them all to fall.
Visible crew/equipment: When Johnny and Roy are on their way to the parade in The Old Engine, in close-ups facing them, the reflection of a crew member's hand holding camera equipment is visible on the hood of the engine.
Visible crew/equipment: When Johnny, Roy, and Chet are removing the woman from her car, the bulging outlines of the mic transmitters and wires are visible on the back, left side of Johnny's shirt, and back, right side of Roy's shirt.
Visible crew/equipment: After Johnny and Roy save the man at Vic's party, when they are leaving, the reflections of crew members and production equipment are visible on the orange surface of the ambulance as it drives away.
Visible crew/equipment: At Vic's party, when Roy and Johnny are walking up the steps of the house (just before seeing Monique), the reflection of the cameraman holding the handheld camera is visible in the door's glass, when he steps backwards as the guys walk in.
Visible crew/equipment: When Roy and Johnny are with Vic (Adam West) trying to outrun the bear, the outlines of the mic transmitter and wire are visible on the back of Johnny's shirt.
Visible crew/equipment: When Roy, John, and Vic are inside stage 3 trying to outrun Charlene, Roy starts climbing down the first ladder, and we can see equipment moving right beside Roy, then when Roy climbs back up and they find the second ladder, more movement can be seen at the bottom of the screen.
Visible crew/equipment: After Station 51 is dispatched to the bomb threat, when the squad and engine pull into the alley, just as Roy stops the squad, the reflection of the cameraman/camera are visible in the spotlight's chrome surface.
Visible crew/equipment: When Roy and Johnny enter stage 3 to search for both Vic and the bear, just after Johnny and Roy split up, as the camera moves forward in Johnny's direction, the moving shadow of the cameraman/camera are visible on the filing drawers, to the left.
Visible crew/equipment: After Squad 51 is dispatched to a man injured at the movie studio, just as they reach the studio, in the shot from the back of the squad, the reflection of cameraman is visible on the lightbar atop the squad.
Transition - S4-E15
Visible crew/equipment: When the three victims of the accident are all in treatment 2 with Morton, in the wide shot just as Brackett, Early, Roy, John, and Gil walk in, at the top of the screen we can see the boom mic dipping down into view.
Transition - S4-E15
Visible crew/equipment: When Dixie and Carol stand in the ER hallway, talking about the three accident victims coming in and being swamped, there are two tape marks on the floor near their feet, where Carol and the other nurse were standing just before Dix walked over.
Transition - S4-E15
Visible crew/equipment: At the amusement park, when Johnny, Roy, and Gil climb up to the ride that is stuck, the outlines of the mic transmitters and wires are visible on the backs of Johnny's and Gil's shirts during the rescue.
Transition - S4-E15
Visible crew/equipment: When Roy and Johnny find the two puncture marks, from the snakebite, on the unconscious man's leg, the outlines of the lav mic transmitter and wire are visible on the back, left side of Johnny's shirt. It's also visible on the back of Roy's shirt after he is hit with the cobra venom, and on the back of Gil's shirt when he brings in the defibrillator.
Transition - S4-E15
Visible crew/equipment: After Johnny and Roy arrive at the amusement park where the boy was injured on the go-kart, when the guy who runs the go-kart track walks over to Roy and Johnny, the outline of the mic transmitter is visible on the back of his shirt, and moments later it's also visible on the left side of Johnny's shirt. Also, when the guys scare the second boy with the huge needle, as he runs away the outline of the mic transmitter is visible on the back of the boy's vest.
Transition - S4-E15
Visible crew/equipment: At the start of the episode, when Captain Stanley leans over to hang up the telephone and walks out of his office, the outlines of the lavalier mic transmitter and wire are visible on the back, left side of his shirt.
Smoke Eater - S4-E16
Visible crew/equipment: When Station 51 is dispatched to the 'structure fire', in the shot facing the squad as it starts to roll out, we can see the black tape covering the lightbar's chrome surface atop the squad, which also vanishes at the incident.
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.