Continuity mistake: Just before the opening credits both Engine 51 and Squad 51 are inside the station. The alarm goes off and when Squad 51 leaves the station Engine 51 has vanished.
Continuity mistake: During the actual rescue of the boy from the overturned car in the water, Roy's, Johnny's, and Chet's shoes are water-type shoes, which then change back to their uniform shoes.
Continuity mistake: After Station 51 is dispatched to 'traffic accident, victim trapped', when they get the anti-shock suit on the boy Roy's watch reads 5:25. Then at the hospital, when Johnny asks Roy about the time, Roy looks at his watch and says "About 5:00."
Continuity mistake: During Roy and Johnny's rescue of the sky diver, the stuntmen are not wearing the fire department uniform shoes, they are wearing different shoes, and Roy's watch differs as well.
Continuity mistake: When Johnny walks into the office to drop off the trash bin, he sees the Chief's clock on the wall and it reads 2:09, but when Johnny brings the clock to Captain Stanley and he gives it to Chet to hide, the clock's hands read 6:44. And when they're all dispatched, the timeout is 14:15.
Continuity mistake: At the scene of the vehicle accident, when the boy is removed from the overturned car, he has a bruise near his chin that reaches below his mouth area. When he's in the ER, that bruise is now twice the size and reaches his cheek area.
Continuity mistake: When Roy and Johnny climb the electrical tower to rescue the sky diver, in the closeups Johnny hangs onto the diagonal cross beam when he reaches out to Lucky, but in the wide shot the stunt double hangs onto the tower's main vertical frame when he reaches out to Lucky.
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.
Continuity mistake: When Karen is assigned to ride along with Squad 51, once they leave the station, en route to the incidents there are only two people seated in the squad instead of three.
Continuity mistake: When Squad 51 is dispatched to 'man down', as the squad heads out of the apparatus bay, the engine we see parked in the bay is the old Crown from seasons 1 and 2, instead of their current Ward LaFrance.
Continuity mistake: When Dixie is having a heart to heart talk with Karen, in the shot facing Dixie she reaches out with her left hand to take the napkin from Karen, but in the closeup it's her right hand that takes the napkin. Additionally, the napkin she takes from Karen is perfectly folded, but it was wrinkled and messy when Karen held it.
Continuity mistake: When Karen first walks into Station 51, her handbag is over her right shoulder, then over her left shoulder and back to her right shoulder again.
Pressure 165 - S5-E7
Continuity mistake: While Johnny and the doctor are in the pressurized chamber with the diver, the guy outside the chamber tells them that they're at 165 and vetting, as he holds the mic up to his mouth with his left hand, but when it cuts to the interior shot, the mic is held up in his right hand.
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.
Pressure 165 - S5-E7
Continuity mistake: At the decompression chamber on Catalina Island, after John and Roy introduce themselves to Dr. Scott, the doctor removes the stethoscope from around his neck and puts it down, but in his closeup it's still around his neck, then in the wide shot it's gone, only to return in closeup again.
The Lighter-Than-Air Man - S5-E8
Continuity mistake: After Gage opens the baby layette wrapping, he and DeSoto leave the kitchen to answer a phone call, When dispatch calls on Engine 51, the rest of the guys start to pile out of the kitchen, but in the next overhead shot the guys are actually exiting the doorway that leads to the locker room, not the kitchen. The interior of Station 51's setup when facing it is, to the right are Captain Stanley's office and the kitchen, and on the opposite side, to the left, are the sleeping quarters and locker room.
The Lighter-Than-Air Man - S5-E8
Continuity mistake: When Station 51 is dispatched to the truck fire, as Captain Stanley responds to the dispatcher Roy and Johnny get into the squad, but we see Marco, Mike and Chet head back to the kitchen instead of getting on the engine, then we see both the engine and squad responding to the incident.
The Lighter-Than-Air Man - S5-E8
Continuity mistake: At the scene of the overturned truck causing toxic smoke, when Chet talks to the driver and then pops out the windshield, in the wide shots the two windshields are intact and not cracked, but in the closeups facing Chet and the closeups facing the driver there are long cracks in the windshield.
Continuity mistake: When Johnny and Roy are at the apartment building with the broken elevator, Roy's watch is gone when they climb the steps, but he's wearing the watch when they enter the apartment, then it vanishes when they head back down. That watch reappears again, disappears and reappears until they go back up to the apartment for the second time.
Continuity mistake: When Roy and Johnny are in the backyard with the couple and the mother-in-law, after Johnny gets off the phone with Brackett, he has the black notebook in his left hand, but in the side shot it's in his right hand, then it returns to Johnny's left hand.
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.