Continuity mistake: When Karen asks Roy and John for an evaluation of that morning's run, a coffee cup suddenly appears near her arm, which promptly disappears, until Roy soon places his coffee cup near her arm when he sits down beside Karen.
Pressure 165 - S5-E7
Continuity mistake: After Johnny discovers that the white stuff he left cooking on the stove has turned green, Station 51 is dispatched to the structure fire, so everyone rolls on the call. When Johnny and Roy return, and Johnny decides to dump all the food he cooked, a large stock pot has mysteriously and conveniently appeared on the counter, where it did not exist when they left.
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.
Dinner Date - S2-E10
Continuity mistake: When the man with three bullet wounds is wheeled into the ER, he's taken into treatment 3 which has a windowless door, but in the shots from inside the room he's in treatment 1 with a window on its door, and the room has a different interior.
Continuity mistake: After Squad 51 is dispatched to the hotel fire, when Roy shouts to John that the woman is about to drop the baby from the third floor, Roy's standing across the street beside the squad, but in the next shot he's suddenly standing in front of the hotel, right behind John.
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: While climbing the tower to rescue the "man" at the top, after Johnny slips and slams into the cross beam, when he and Chet are heading back down the tower, the two lights attached to the tower keep switching from the right side to the left side, depending if it's a closeup of them or a wide shot of their doubles. Additionally, in the closeups the lights are large and round, but in the wide shots one of them is a small square.
Paper Work - S6-E11
Continuity mistake: When John's in the storm drain with the boy, in the closeups the water rushing from the broken hydrant has a very strong current, and Roy's holding the boy's head up out of the water, but in the wide shots the current is nearly calm, nowhere as intense as the closeups, and Roy's not holding the boy's head.
Captain Hook - S6-E8
Continuity mistake: During the police chopper rescue, three ropes are tied off onto Engine 51's eyes, and when Mike backs the engine up while the stokes carrying Frank is pulled up, in shots facing the engine the three lines are being pulled backwards simultaneously, but in the shots of Marco, the stokes, and the ground, only the line with the stokes is being pulled up, the other two ropes are lying on the ground completely still.
Continuity mistake: When Roy and John are helping Jeanine get her head unstuck from the table, Jeanine's braid is very loose and coming apart, but when her head is free and she jumps into her mother's arms, Jeanine's braid is braided properly.
Continuity mistake: Dispatched to the structure fire in the middle of the night are Station 51, Engine 95, Engine 105, and Truck 107, but on scene we see Engine 800, Engine 801, and also Engine 10, which is all footage from the first season's pilot episode "The Wedsworth-Townsend Act."
Continuity mistake: After treating the girl who had a soda pop bottle explode in her face, when John and Roy are carrying the stretcher out the door, they're facing the stretcher and each other in the interior shot, but in the exterior shot John has turned around, with his back facing Roy while carrying the stretcher.
Peace Pipe - S2-E5
Continuity mistake: When Roy and John climb up to the scaffold John removes his gloves, but the stuntman keeps his gloves on for quite a few of the following shots, until he also removes his gloves.
Peace Pipe - S2-E5
Continuity mistake: On scene at the drunk's car accident with the little girl trapped in the car, in the shots facing the girl's mother she's standing with Vince behind the back of the car, near the crowd of bystanders, but in Roy's closeups while he's in the car with Debbie getting her vitals, we see the mother's legs (note her yellow polka-dot dress) right behind Roy, near the open front passenger door.
Peace Pipe - S2-E5
Continuity mistake: After watching the movie on TV, Chet says he has royal Indian blood, and when Johnny walks over to Chet he puts his arm around Chet's shoulder, and tells him it's called, "White man royalty syndrome," then it cuts to a closeup of Roy, and we see Chet still standing by himself.
Continuity mistake: After Early tells Dixie about the patient with an unknown illness, in the shot from the hallway, we see Carol taking him into treatment 4, which has a windowless door, but when Morton is examining him in the shot from inside the room there's a window on the door (looks like treatment 6).
Continuity mistake: When the woman from the car accident is brought to the ER, she's put into treatment 4, as mentioned by Dixie and all three doctors, and it has a windowless door, but when Early and Morton are speaking to the patient about the car accident, they're all in a treatment room with a window on the door (looks like 6, the one opposite the nurses' station).
Continuity mistake: When Roy and Johnny are with the injured hiker (John Travolta), after the gear-filled stokes is lowered to them Johnny places it right behind the hiker's head, but in the hiker's closeups the stokes basket vanishes, only to reappear in wide shots.
Continuity mistake: While the children from the bus accident are being lowered on 43's snorkel, Roy and Johnny are in the bus with the nun. Then even though quite some time has passed, by the time Roy and John are ready to free her from the wreck, it cuts to the shot of the same children still being lowered on the snorkel.
Continuity mistake: After Sister Barbara is brought to the ER, when Dixie tells Roy to get coffee with her, Dixie has long nails with light colored polish as usual, but when it cuts to the closeup of Dixie's hands getting coffee from the urn, the long nails are unpolished.
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.