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.
Continuity mistake: When all the guys enter the apartment with the doctor lying on the couch, John's carrying the Biophone with his right hand and starts to place it down, but then it cuts to another angle and John's holding the Biophone in his left hand as he places it down.
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.
Visible crew/equipment: After Dr. Early tells Mr. Jefferson that he knows who he is, it cuts to Johnny at the table with the typewriter, and the shiny chrome surface of the coffee pot reflects multiple set lights.
Continuity mistake: At the scene of the vehicle accident, once Vince wraps the gauze around the head of the driver of the pickup truck, the same bystanders are standing in two places at once - on the sidewalk beside Engine 51 and across the street beside Squad 51.
Visible crew/equipment: After we see Marco and Captain Stanley heading up to the roof, it cuts to a shot in the elevator when Roy says "The firemen are working as hard and as fast as they can, to get us down from here," and the crew's moving shadow can be seen on the left, where the camera is located at the elevator doorway.
Continuity mistake: When John and Roy rappel down together after John's rope kinked up, as they reach the bottom Roy and John remove their helmets, but as Wally rappels down both paramedics still have their helmets on in the overhead shot.
Continuity mistake: After Early tells Dr. Ned that he thinks he has mononucleosis, when Early leaves the room, the nurse that's in the room with Dixie walks away from the patient to the other side of the room, but in Dr. Ned's closeups that nurse is still standing behind him while he talks to Dixie.
I'll Fix It - S4-E2
Visible crew/equipment: When Roy and John walk into the grocery deli, a few of the location shoot's array lighting are reflected on the glass door.
Inventions - S3-E22
Continuity mistake: When Chet's wearing his suction cup shoes, John uses the hose to wet the area around Chet's shoes, and then places the hose down on the ground, but in the shot from inside the van John's still holding that hose.
Visible crew/equipment: When Station 51 is dispatched to the industrial accident, with the big guy suffering from a chemically induced psychosis, the outline of the mic transmitter and wire are visible on the right side of the big guy's T-shirt.
Visible crew/equipment: When Station 51 is dispatched to the structure fire at the Kiddytime Toy Factory, while en route there's a shot from the POV of the top of Squad 51, and the reflection of the cameraman and the camera can be seen on the lightbar's chrome surface.
Continuity mistake: At the start, when Chet tacks the notices up on the bulletin board, the papers are tacked to the board differently between the closeups and wide shots.
Propinquity - S3-E20
Continuity mistake: Just before the ambulance Roy is riding in is involved in the collision, we see a crowd of people at the corner near the stop sign, but in the next shot they've all vanished, only to reappear just as the vehicles collide.
Propinquity - S3-E20
Continuity mistake: After they load the woman from the wrecked car into the ambulance, Roy and an ambulance attendant are riding in the back with her. In the shots of the moving ambulance, until it's involved in the traffic accident, we should be able to see Roy and the attendant through the windows, but they're simply not there.
Continuity mistake: Before Old Bill wakes up, Brackett, Morton, and Early are talking in the hallway outside Bill's room, and the hallway is a big, wide open space. After Bill wakes up, Dixie goes out to the hallway to get Brackett, and when they walk into Bill's room we can see the hallway behind them, and it's a fraction of the size it was before, only about 4-5 feet wide now.
Continuity mistake: After bringing Old Bill to the ER, when Squad 51 gets back to the station, in the shot of the squad driving backwards toward the driveway, the engine we see parked in the apparatus bay is the Crown from the first two seasons, not their current Ward LaFrance.
Continuity mistake: When Station 51 is dispatched to 'man down', Cindy and her mother are standing in front of the rear bay door, but they vanish in the next shot as the guys get ready to leave.
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.