Revealing mistake: When the critical boy who ingested the ant poison is being wheeled into the ER's treatment 3, we can see Johnny laughing, and obviously since absolutely nothing about the situation is funny, we know it's Randolph Mantooth just cutting up during the take.
Visible crew/equipment: When Johnny is in the ambulance with the boy who ingested poison, the shadow of the cameraman holding the handheld camera is visible on Johnny as he sits beside the stretcher.
Continuity mistake: When Station 51 is dispatched to an 'unknown type rescue', the woman who opens the door tells them she didn't call, and when Roy asks her if he and Johnny can check on her sick husband, Roy's second shirt button is open and his undershirt is visible, but in the next shot it's buttoned up again.
Other mistake: When the squad and engine roll up on the scene of the bulldozer accident in the junkyard, just as the guy runs up to inform them about the victims, have a look at Squad 51's license plate number because it is not the normal prop plate number E999007.
Visible crew/equipment: When the boy who ingested ant poison is being wheeled into treatment 3, in the shot from the hallway we can see the electrical cord and plug lying across the floor, but in the next shot from inside treatment 3, that cord has vanished.
Revealing mistake: When Cindy and her mother come to see the station, Cindy goes to the closet with the gear, and as she opens the door Cindy starts laughing before Johnny even gets hit by the phantom, and then she glances toward the camera grinning because of the prank.
Other mistake: After Johnny gets hit by the phantom in the apparatus bay, Station 51 is dispatched to an unknown type rescue at 617-1/2 Kimball Rd, and before the dispatcher even gives the address, Mike has already located the area on the map with his finger.
Continuity mistake: At the start of the episode, after Chet takes a spoonful of hot cheddar cheese the bowl is near his plate, but when it cuts to facing the other guys that bowl is on the other side of the table near Marco, then back and forth again.
Continuity mistake: When the boy who ingested ant poison is laid down on the gurney, the safety belt is wound around the gurney's side bar and clasped, but when exiting the house and loaded into the ambulance the safety belt is directly around the boy.
Continuity mistake: When Johnny goes to the closet to get the mop, because he's 'latrine officer of the day', he gets hit by the phantom, and all the guys run out of the kitchen to see Johnny wet again, so when dispatch drops the tones they all head for the vehicles and Captain Stanley removes his jacket. Then next shot all the guys are running out of the kitchen, as if they were all still there, and Stanley is wearing his jacket.
Continuity mistake: When Old Bill is wheeled into treatment 3, there's a pillow under his head and the gurney he's lying on has grey trim, horizontal bars under the bed and flat steel plates over the wheels, but when it cuts to inside treatment 3 as he's brought in, the pillow has vanished and the entire style of the gurney he's lying on is completely different.
Revealing mistake: While John's in the ambulance with the boy who ingested the poison, after John inserts the esophageal airway and uses the ambu-bag, just as John says, "Real good," if we look out the window behind the attendant, we can see Universal's GlamourTrams (a set of three trams) driving by in the distance. The footage inside the ambulance was shot while the ambulance drove around Universal's lots.
Continuity mistake: After Station 51 is dispatched to 'man down' and realize it's Old Bill when they look through the window, when Roy and Johnny climb through the window their gear is handed in to them, and John takes the drug box with his left hand and Biophone with his right, but in the next interior shot John's taking them with the opposite hands.
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.
Visible crew/equipment: After Station 51 responds to the unknown type rescue, Engine 51 leaves on another run, but when Johnny and Roy go into the house with the wife of the man who lost his voice temporarily due to the dieffenbachia plant, the bulging outline of the lavalier mic transmitter and wire are visible on the back of her white robe.
Visible crew/equipment: After Station 51 is dispatched to the bulldozer accident, just before Engine 51 comes to a stop at the junkyard there's a shot from the perspective of Engine 51's roof, with the Beacon Ray dome light in front, and on the light's red and chrome surface we can see the reflection of the camera mounted on the roof behind the dome light.
Visible crew/equipment: After the boy who ingested the ant poison is loaded onto the ambulance, when the back doors are shut, the reflection of the location set lighting is visible in the ambulance window and on its surface.
Visible crew/equipment: After Johnny carries Cindy down from the treehouse, when Cindy's mother joins them, the bulging outline of the lavalier mic transmitter is visible on the back of her white sweater.
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.