Continuity mistake: At the construction site, after the younger patient has been taken to the ambulance, when Roy tells Johnny that it was pretty good radio work, Johnny's holding his helmet, but in the next shot as Johnny stands up his helmet is gone, though there is a helmet near the drug box behind him.
Continuity mistake: When Roy and Johnny are on the roof with Harriet, we can see the shadow being cast by the utility pole on the street down below, and when the police car shows up moments later that shadow has changed significantly. (00:12:40)
Continuity mistake: When the guy (Michael Conrad) with the gunshot wound is being wheeled out of the treatment room there is nothing on his face, but in the shot from the hallway as they exit the room suddenly he has a tube inserted into his nostril with tape holding it in place.
Continuity mistake: While Squad 51 is out on the run (quite literally) with the female OD, Johnny gets a cut on his elbow which he keeps fidgeting with even after it's bandaged. When Roy and Johnny get back to the station and see The Old Engine, Johnny's cut has vanished.
Continuity mistake: When Johnny starts chasing Harriet down the street, in Johnny's closeup when he passes the white house (right after the yellow house), there is a light colored wagon-style car parked in the driveway, but in shots from other angles there is a green 2-door parked in that driveway.
Continuity mistake: When the squad rolls up on the OD victim's residence Roy drives the squad over the little fence and bends it. When he takes off the gate is back in its original position.
Continuity mistake: After 17's Captain Harmell has fallen through the warehouse roof, when Roy wraps the tape around Harmell's leg splint, the entire splint is covered by tape when they lift him up the ladder, but when Harmell is carried out of the snorkel, there is much less tape - it's wrapped around the splint only 5-6 times.
Continuity mistake: When 51's guys are at the back of the station with The Old Engine, Johnny tries cranking it and his watch reads 5:20. Then after Squad 51 is dispatched to the heart attack, when Johnny's on the line with Rampart after defibrillating the patient his watch reads 11:15, then after administering atropine, his watch reads 2:30.
Continuity mistake: When Johnny and Roy walk into Councilman Wilby's home, Wilby's wearing a buttoned up shirt and tie, and they place the O2 tank near his feet, but in Wilby's first three closeups the O2 tank is already behind the couch by his head and his shirt is unbuttoned with no tie, but in the wide shots Roy and Johnny haven't even made those changes yet.
Continuity mistake: During boat rescue, when Johnny's on the Biophone with Rampart, right after Brackett tells them to continue oxygen and maintain D5W IV, Roy has his hand out with the IV bag and tells 81's guy to hold it, but in the next shot 81's guy is taking a BP cuff from Roy's hand, not an IV bag.
Continuity mistake: When Station 51 is at the scene of the plane crash, in the long shot Roy climbs down to the wrecked plane and tosses his helmet, but wears his gloves when he starts looking for survivors, then in the next closeup his gloves have vanished.
Continuity mistake: When Roy and Johnny are on scene at the boating accident, John contacts Rampart, and in the closeup of the base station telephone, we see the old reel-to-reel tape recorder that was used during season 1, behind the old GE Deskon 3-button telephone. In the next shot Rampart's base station is back to normal.
Continuity mistake: When the stokes with the boating accident victim is being loaded onto the Harbor Patrol boat, Roy's standing behind The Boat in the water and Johnny's in The Boat with the stokes, but in the next shot they've switched places, Roy's in The Boat and Johnny's behind The Boat. Others have also switched places between shots.
Continuity mistake: When 51's guys are standing around Johnny's bed looking at the cat, in the cat's closeups she is facing the locker room, but in the other shots she is facing the opposite way, with the guys behind her.
Continuity mistake: When Brackett is in his office talking to Patsy's manager, he's paged and then told, "Treatment room 2, STAT," and he answers, "On my way," but Brackett doesn't rush to treatment room 2, he goes to room 230 which is Patsy's room, and Early even calls for a code blue in room 230.
Continuity mistake: When Brackett and Morton are with Patsy in her hospital room, there are two closeups of the Datascope 850, but there's an entirely different unit at the foot of Patsy's bed monitoring her EKG, not the Datascope 850. The same thing happens again later, when Brackett rushes in and Early tells him that Patsy was throwing more PVCs.
Continuity mistake: At the rock quarry, after Johnny tells Captain Stanley that they need the Stokes and a jack, Johnny removes his helmet, and while Jason holds Johnny's helmet, Johnny tosses the rope below, but in following shots Johnny's wearing the helmet again.
Continuity mistake: At the start, when Johnny and Roy get back to the station from their run, Roy leaves two cabinet doors wide open when he gets two coffee cups, but in the next shot as he shakes Jason's hand, those two doors are suddenly closed.
Heavyweight - S3-E5
Continuity mistake: At the start, after Station 51 is dispatched to the apartment fire, when a musician asks Captain Stanley for help removing instruments from the burning building, the next shot showing Truck 98 rolling up is footage from 2x13, "Drivers", during the fire at the Atlas Hotel. We can even see the smoke through the Atlas Hotel's windows, and Squad 51 parked across the street. More footage from the Atlas Hotel fire is shown when Engine 16 rolls up. Additional footage from other episodes are shown as well, when we see helmets and rigs bearing company numbers that were not called to this fire.
Heavyweight - S3-E5
Continuity mistake: When the little boy who received an electric shock is brought into the ER, in the shot from the hallway he's taken into treatment 4, which is beside the nurses' station, but in the next shot from inside the room, we can see treatment 2 on the opposite side of the hallway, which is next door to treatment 4. This means they're actually in treatment 1, not 4.
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.