Visible crew/equipment: During the rescue at the construction accident, when the man with the back injury is hanging from his line and is lowered after Roy untangles the block, we can see that in addition to the rope wrapped around the man there's wire and support that go under the man's jumpsuit. The wire/support are gone once he's lying on the balcony and they remove the rope.
The Wedsworth-Townsend Act - S1-E1
Other mistake: On scene at the "possible electrocution", when John is on the raised snorkel waiting for the power to be cut, we hear the worker who is up on the utility pole whistling to grab his co-worker's attention, but the subtitles read that it's John who whistles. Subtitles from Universal Studios 2010 DVD.
Other mistake: When Roy and Johnny are at base camp during the fire, they're dispatched to the incident at Jawbone Canyon. While en route, Battalion 5 orders Engine 51 to approach from the north, and we hear Captain Stanley respond, "Engine 51, 10-4," but it's odd that the subtitles read that Johnny is the one who responds. Later, after Tanker 44 tanks 51, Chet says, "Cap, we've got a charged line," but the weird subtitles read, "Captain's going to throw us a line." Subtitles from Universal Studios 2010 DVD.
Continuity mistake: After the cropduster crashes, when Roy and Johnny pull the pilot out of the overturned aircraft and begin working on him, Johnny's medical holster with penlight, forceps and scissor is clipped at his right hip and the other holster's at his left hip, but when Johnny shouts to Chet about giving the victim oxygen, Johnny's holsters have switched sides.
Other mistake: When Squad 51 is on scene at the drowning incident, the victim's wife is wearing very unusual rings. One ring has a jumbo orange ball, another has a large cluster of small gold balls, and the third has large black and white pearls. Later, when the models are at the station they are wearing identical rings as seen in the previous scene, Suzanne is wearing two of the prop rings and Kathy is wearing the pearl ring.
Visible crew/equipment: When Johnny jumps from the third floor ledge onto the lifenet, in the shot of his actual jump we can see a cameraman wearing jeans at the bottom left corner of the screen, who's holding a handheld camera shooting footage while lying on the street. The angle of that footage can be seen just as Captain Stanley shouts, "Gage, you first," and also when they walk the lifenet over to their left, before Cap shouts, "Okay, Roy!"
Visible crew/equipment: When Engine 51 rolls up on scene at the paint factory structure fire, Captain Stanley heads towards the street corner, and we can see the actor's white T-mark on the ground before he gets on the HT.
Heavyweight - S3-E5
Visible crew/equipment: When the guy is stuck in the tree after his hang gliding accident, John ties the rope around the branch and begins to saw the branch while Roy uses that rope to slowly lower the branch. The problem is that just as the branch nears the ground, we can see the production crew's thin double lines securing the branch at the top right of the screen, and then those lines vanish when Roy joins John.
Other mistake: After the explosion occurs in Rampart's basement, when Engines 236 and 73 roll up on scene, we can see the engine companies' numbers are covered up atop their cabs, presumably to conceal the engine companies' real numbers.
Paper Work - S6-E11
Visible crew/equipment: After rescuing the foreman and secretary from the structure fire with nitromethane drums, when Roy and John load them onto the ambulance, as Roy shuts the doors the reflections of multiple array lighting rigs are visible on its window and surface.
An Ounce of Prevention - S6-E13
Continuity mistake: While John and Roy begin rehearsing in front of Marco and Chet, when John lights the flame his watch reads 10:00, but just a few minutes later when John puts the sawdust into the strainer his watch reads 10:30. When Squad 51 is dispatched to "sick child," timeout is 12:13, and after John and Roy get back to the ER the second time after searching the garage for the poison it's 1:05 at the ER. Then when they're on the Tom Jensen Show, as Roy tries to light the flame John's watch reads 11:30, but when he and Roy are treating the electrical shock victim, his watch reads 4:00.
It's How You Play the Game - S4-E19
Visible crew/equipment: After the man with the herniated lumbar disc is removed from the waterbed and loaded onto the ambulance, when John gets into the squad, the reflection of a crew member is visible in the passenger side wing mirror.
Visible crew/equipment: When Roy drives off in the squad just as Animal Control shows up at the store with the tiger, we can see multiple reflections of array lighting on the vehicle and also the store's windows across the street.
Continuity mistake: When the Animal Control guys are dispatched to the fire in the canyon, the rearview mirror in their vehicle vanishes in the close-ups.
An Ounce of Prevention - S6-E13
Continuity mistake: After Early has examined the woman who was stuck up on the ferris wheel with her husband, he tells her she could go to the waiting room, and when Early leaves treatment 2 the stethoscope is around his neck, but next shot from the hallway as he exits the stethoscope is gone.
Captain Hook - S6-E8
Other mistake: When John, Roy, and Chet are standing near the stove talking about how much they enjoyed Hookrader's party, there's a can of cleaning powder which has tape swirled around the can to hide the recognizable design and its brand name, which is Ajax.
Continuity mistake: When Roy and John are talking to Vic at his party, his manager's cigar changes length repeatedly, from short to long and back again, depending on the camera angle.
Visible crew/equipment: While en route to the accident, just as we hear the dispatcher inform Engine 51 that the fire is out, in the exterior shot of Squad 51 there's black tape covering much of the lightbar's chrome atop the cab, which vanishes when they roll up on the accident scene.
Revealing mistake: When Roy's in the ambulance with the man who was rescued from under The Boat, he's on the Biophone with Rampart, and just after Roy says, "So we've occluded the arterial flow in the right arm," in the next shot from inside the ambulance, we can see that they pass a couple of parked GlamourTrams. The ambulance drives around Universal's lot while shooting the footage inside the moving ambulance, en route to Rampart.
Smoke Eater - S4-E16
Continuity mistake: When John and Roy are with the possible MI, while Roy's setting up the IV bag John's on the Biophone with Rampart, and after Brackett orders the IV TKO with MS, we see that Roy's pant leg has nothing on it, but then it cuts to the closeup and suddenly there are strips of torn tape (for IV as usual) on Roy's pant leg.
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.