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.
Heavyweight - S3-E5
Visible crew/equipment: When Roy and Johnny are with the guy who got stuck in the tree while hang gliding, the outlines of the mic transmitters and wires are visible on the back of the victim's sweater and also the back of Johnny's shirt as he saws the branch, and then carries the victim to the Stokes.
Heavyweight - S3-E5
Other mistake: When Chet is preparing the lasagna, then tells Johnny that he's preparing 'rutabaga delight' especially for him, the green container of parmesan cheese has tape covering the brand name, though it looks like it's the Kraft brand.
Heavyweight - S3-E5
Continuity mistake: At the start, after Station 51 is dispatched to the apartment fire, when a musician asks Captain Stanley for help removing instruments from the burning building, the next shot showing Truck 98 rolling up is footage from 2x13, "Drivers", during the fire at the Atlas Hotel. We can even see the smoke through the Atlas Hotel's windows, and Squad 51 parked across the street. More footage from the Atlas Hotel fire is shown when Engine 16 rolls up. Additional footage from other episodes are shown as well, when we see helmets and rigs bearing company numbers that were not called to this fire.
Heavyweight - S3-E5
Continuity mistake: When the little boy who received an electric shock is brought into the ER, in the shot from the hallway he's taken into treatment 4, which is beside the nurses' station, but in the next shot from inside the room, we can see treatment 2 on the opposite side of the hallway, which is next door to treatment 4. This means they're actually in treatment 1, not 4.
Heavyweight - S3-E5
Character mistake: When Johnny first contacts Rampart via landline about the stabbing victim, while Roy is across the street with the gunshot victim, Brackett gets on the line and asks Johnny if he started an IV, to which Johnny replies no, then he asks what the vitals are. Johnny has only just made contact with Brackett about this patient, so Johnny could not have started an IV without the doctor's consent, Brackett knows this. This goes against established procedure.
Heavyweight - S3-E5
Visible crew/equipment: When Roy and Johnny are with the man who was injured by a gunshot, Johnny goes across the street to treat the stabbing victim, and just as Johnny and the others enter the living room, the shadow of the moving boom is visible on the wall to the right.
Heavyweight - S3-E5
Continuity mistake: At the structure fire, after Roy helps the pregnant woman down the stairs, when Johnny brings the O2 and blankets for her, we see that Johnny's wearing a SCBA tank with no markings. However, after Roy tells Johnny to take off, when Johnny hurts his shoulder, his tank has two large stickers - a white and a red.
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.