Welcome to Santa Rosa County - S6-E10
Continuity mistake: When getting the climbers off the mountain, the Ford letters on the tailgate are muddy and blanked out, but are not in the scenes where they're transporting the climbers in the pickup bed.
Factual error: When Roy is electrocuted and falls from the roof, after Karen uses the defibrillator paddles on Roy, she lifts both paddles, looks at the EKG monitor and says "He's converted." How exactly could Karen have known that he's converted? It's impossible for the EKG monitor to show anything at all. Either the defib paddles have to be in contact with Roy's body for the "quick-look" to get a reading, which they weren't, or the ECG electrode discs have to be on Roy's chest connecting him to the EKG monitor, and they weren't. As an aside, just watching Marco having problems attaching the air mask, and quickly glancing up towards the camera frustrated, then giving up is priceless.
Revealing mistake: At the apartment complex fire, after Johnny is knocked unconscious by the explosion, when the Pasadena fireman finds him and has to lift him up, it's funny how even though Johnny's unconscious we can see that he actually helps to stand himself up, so the fireman can lift him up and carry him out.
The Wedsworth-Townsend Act - S1-E1
Other mistake: At the start, on the way to the structure fire one of 10's rigs has license plate number E180174, but at the fire we see 127's engine has the same license plate number E180174.
Other mistake: On scene at the traffic accident, when the woman and the boy with non-serious injuries are seated at the back of the ambulance, neither Roy or Johnny are going along with them to Rampart, yet Johnny puts the drug box inside the back of the ambulance with them, and the ambulance drives off. With their drug box! Captain Stanley even says that he'll advise dispatch that they're available for a run at the scene, while the guys will be looking for the dog.
Visible crew/equipment: After Johnny and Roy save the man at Vic's party, when they are leaving, the reflections of crew members and production equipment are visible on the orange surface of the ambulance as it drives away.
Visible crew/equipment: When Roy has trouble sleeping in the middle of the night, he gets up, and when he goes to the bathroom sink, there is a fully dressed crew member whose reflection is visible in the mirror, as he moves around and looks through the door window towards the actor. Then 51's tones drop, and in the next shot we see that all the other guys of Station 51 have been lying in their beds, before getting up and putting on their turnouts.
The Promise - S3-E11
Visible crew/equipment: Once the ledge rescue is over, after Johnny tells Brackett that he could put in a good word for him to join the paramedic program, when Roy opens the squad door to get in, the wing mirror offers up nice reflections of a few crew members.
Revealing mistake: At the apartment complex where the jet fighter had crashed there's an explosion, and when one of the firefighters becomes engulfed in flames his helmet falls off, and the special fireproof headpiece that the stuntman is wearing is visible.
Visible crew/equipment: During the structure fire, Johnny and Roy rescue the security guard, and when Roy breaks the window with the chair, we can see a couple of crew members, equipment, and lighting on a tripod, outside down below.
The Wedsworth-Townsend Act - S1-E1
Visible crew/equipment: When Station 10 is dispatched to the factory fire, a few shots after the closeup of 105's door that reads "fire dept deluge", there's an overhead long shot of the men using the hoses against the fires in the doorways, and a cameraman wearing blue, holding a handheld camera, is visible sitting at the back of a squad.
Revealing mistake: After the two drivers from the traffic accident walk off holding hands, and Johnny tells Roy what happened with Barbara, while Roy explains "body-language" to Johnny, we can see the white tape with "Kevin" inside Roy's helmet.
Visible crew/equipment: During the emergency surgery on the boy who was shot with a pellet gun, the wired microphone that is taped to Brackett's shirt with black tape and hidden under his white coat becomes visible when he puts the gloves on, and during the surgery.
Visible crew/equipment: Just after Herbert leaves the station in the morning, dispatch sounds the alarms, and when Roy and John are in the squad while the dispatcher begins talking, there are nice reflections of the camera, reflector screen (in the background), and crew members/cameraman who move around, that are visible on the surface of the spotlight. Additionally, the shadow of the boom/mic is perfectly visible on the windshield as it moves down.
Revealing mistake: At the start of the episode, we see Squad 51 speeding toward their destination, and when the camera cuts to the woman in front of the market, she's waving her arms to the squad somewhere in the distance. But notice that while Rosa is looking to her left and waving, we can see Squad 51's reflection in the window (with the liquor bottles), as they are parked right there, just off-screen waiting for their cue to "speedily" pull up.
Visible crew/equipment: When Station 51 arrives at the salvage yard's fire, Johnny gets out of the squad, and when he puts on his turnout coat as the camera zooms out, a dark haired crew member wearing a short sleeve white shirt is visible at the lower right corner of the screen.
Other mistake: In the interior shots of Station 51 (the studio set), when facing the rear apparatus bay door, the right wall has a door to Captain Stanley's office, a very large map, the radio receiver base station where they respond to dispatch, the kitchen doorway, and a double-door closet, that's it. However, when Station 51 is shown in the exterior shots (the real Station 127 aka 51), as either the engine or squad exits when the apparatus bay door is up, we see that the right wall has many more doors on that wall. Additionally, the opposite wall on the set has only two doors - one to locker room/bathroom, and one to the dorm, however at the real 127's, that wall has three doors - two of them are to the dorm.
Visible crew/equipment: During the rescue of the two guys up on the scaffold, when Gage is putting on his pack and harness, an actor's T-mark is visible on the ground, which Captain Stanley promptly stands upon when he asks Gage if he has his handy-talkie.
The Wedsworth-Townsend Act - S1-E1
Visible crew/equipment: As the camera pans to the left at the start of this episode, while everyone is asleep in the dorm upstairs, a crew member standing near the production's lighting equipment is visible between Squad 10 and the wall. Also note that the lighting equipment is gone when the guys are dispatched.
Inventions - S3-E22
Visible crew/equipment: At the site of the major chemical leak, after Johnny falls from the pipes and Roy lifts him up, a couple of shots later there is a medium shot of one of 105's guys on Deluge 105 pumping out water, and we can see a cameraman (filming Deluge 105's closeups that we see during this scene) holding a handheld on the right of the screen, behind the pillar.
Answer: I believe you are speaking of the old man, Mr. Wilson. He's played by J. Pat O'Malley.
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.