Revealing mistake: When Roy and Johnny are in the radioactive lab, loading the unconscious doctor with severe radioactive poisoning onto the stretcher, note that the unconscious doctor is lifting his own left arm, and moving it onto the stretcher so it's resting beside him properly.
Continuity mistake: Before 51's guys rescue the burglar trapped in the air conditioning duct, Vince's helmet has a highly polished and reflective surface, but when Vince reads the Miranda rights he's wearing a different helmet, it now has a matte surface.
Continuity mistake: When Roy tells the other guys of 51 what they need to do to rescue the doctor, once they're in the hot room, in the wide shot Roy's holding the handie-talkie in his right hand as he's gesturing with that hand, but when it cuts to Roy's closeup the HT has vanished from his right hand, as he's still gesturing.
Character mistake: When Roy and Johnny are waiting outside the radioactive lab, Roy sends Marco and Mike to replace Chet and the captain. When Chet and the captain come out, the captain points to Chet and then points up the hallway, while he says "All right, take off you two," even though it's only Chet who's heading outside to be decontaminated, and he could not have meant, "All right, take off you too," for the same reason.
Visible crew/equipment: A few shots after Johnny informs Brackett of the victim of the radiation incident, there's a shot of the ER with two orderlies pushing a gurney towards the camera, and the two actors' tape marks are visible on the floor at the bottom of the screen, just before Brackett and Dixie stop there, when Brackett tells Dix to notify the radiation security guard.
Continuity mistake: When Johnny and Roy go into the radioactive lab, Johnny removes his glove to check the doctor's carotid pulse and when they walk through the doorway both his gloves are off (he's holding them), but in the next shot exiting the doorway both of Johnny's gloves are back on.
Visible crew/equipment: When the babysitter runs into Rampart carrying the boy, both Dixie and Brackett are standing at the nurses' station talking and an actor's white T-mark is visible at Dixie's feet.
Visible crew/equipment: Just as Dixie lets the unconscious teenager's parents walk into the ER treatment room, the actor's T-mark is visible on the floor behind Gage's legs, a moment before Brackett stands at the mark.
Visible crew/equipment: When Brackett, Dixie and Early are working on the unconscious little boy, once Brackett says to go with the pacemaker, multiple black T-marks are visible all over the floor - three under the gurney and one near the cart. Another actor's white tape mark is visible under the gurney (partially blocked by the green oxygen tank), where both Early and Dixie stand at different times.
Other mistake: When Roy's talking to Dixie while John's waiting out in the squad, a call comes over the HT that Roy's holding, and Squad 51 is asked to respond to a 'possible heart case'. Roy pulls a piece of paper out of his pocket, and as we hear the dispatcher giving the address, we can see Keven Tighe softly mouthing the address at the same time that it's being given for the first time.
Other mistake: When the boy is brought to the ER by his babysitter, they hook him up to the ventilator and we see the bag dramatically showing inflation and deflation in the closeup, but in the wide shots the bag is deflated and doesn't move.
Revealing mistake: At the end of the 'crashed plane in a tree' rescue, Tom falls upside down in front of Roy and John, who are standing on branches way high up in the tree. Then just as the scene ends and the screen fades out, we can still see Gary Crosby (Tom) having fun jumping hard up and down on that "tree branch" that he's now also standing on, and Randy Mantooth starts cracking up.
Continuity mistake: When the babysitter runs into Rampart with the child who swallowed phenobarbital pills, Brackett picks the boy up and carries him into treatment 5 (window on door), but in the following shots from inside the room we can see they're actually in treatment 2 (windowless door and set up differently). Then after they place the pacemaker Dixie leaves the room, and in the shot from the hallway she's coming out of treatment 5.
Continuity mistake: After Sharon calls out Dr. Early's name in the hallway, because paging him didn't occur to her, when she finds Early they walk into treatment 2 in the shot from the hallway, but in the shot from inside the room they're all in treatment 5, not 2.
Visible crew/equipment: When Squad 110 pulls up to Chopper 14, the reflection of the reflector screen is visible on the squad's surface, and when all the guys climb into the chopper, the reflector screen's reflection is visible again.
Continuity mistake: After John makes a sarcastic comment, while he and Roy are in the treatment room with Dr. Early, Roy takes the squad's oxygen tank with him when he leaves the room, but when he exits the ER to get into the squad, the oxygen tank is gone.
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.