Continuity mistake: When Dixie gives John a tetanus shot because he fell from a skateboard onto cactus, we know they're all in treatment 1, because when Johnny and Roy are at the open door we can see the door and wall (with fire extinguisher) on the opposite side of the hall, but in the next shot from the hallway he and Roy are leaving treatment 4, which is opposite treatment 3.
Continuity mistake: While the boy who has cyanide poisoning is in the ER, Dixie looks through his clothing and finds carved peach pits, and when she directs Brackett's attention to all the carved pits, the items change when it cuts to the closeup. Additionally, that closeup starts out being farther, and we can see that Dixie is not beside the table before it zooms in.
Continuity mistake: When Station 51 is being dispatched to the fire and explosion at Martell Industries, the other companies called are Station 36 and Engine 14, but we see Engine 236 at the scene even though they were not called. This is before Captain Stanley asks dispatch for the second alarm.
Continuity mistake: During the fire at Martell Industries, when Roy and Johnny make a mad dash out of the building before the explosions, and midway Roy's helmet falls to the ground as he keeps running, but in the next shot when he and Johnny reach the engine and dive to the ground, the helmet is hanging around Roy's neck.
Continuity mistake: When Dick introduces Art Fromich to Roy and John, in the wide shots the Biophone is lying on its side atop the squad, but in each of Roy's closeups the Biophone is upright.
Continuity mistake: After Roy and Vic run out of Stage 3, when Johnny backs up and bends down, we can see Charlene, the bear, on all fours, then in the next shot the bear is walking on her hind legs toward the door, but in the next shot from behind Johnny the bear is still on all fours and further back again.
Continuity mistake: During the house fire, Marco's holding the hose behind Chet, while Chet is kicking open the front door just before it flashes, but in the next shot both Chet and Marco are manning the hose when the fire flashes, knocking them down the stairs.
Smoke Eater - S4-E16
Continuity mistake: When Billy's mother waits in the hallway while Early examines Billy, the window behind her is on the same side as the ER's receiving entrance. Note that outside the window there's a blue metal shade at the top, which does not exist in any exterior shots of that side of the ER.
Transition - S4-E15
Continuity mistake: When Gil is assigned to ride along with Squad 51, en route to the incidents there are only two people seated in the squad in the shots shown.
Continuity mistake: While Johnny tries to reach the man who fell over the cliff, when the bicycle falls to the bottom of the canyon both tires break free from the frame, but when the officer retrieves the bicycle, only one of the tires is off, the other is undamaged and on the frame.
Continuity mistake: When John and Roy walk into the house with the pregnant gunshot victim, only John's wearing a helmet and he places it on the floor near the victim's husband, but in all of John's closeups (from the unusual POV looking up at him) his helmet is on the counter. Additionally, there are blue glasses upside-down on the side of the dish drainer, but in those closeups of John the glasses have vanished, and the glasses vanish again when Roy helps the husband get on his feet. Also notice that there's now a blue glass in the sink.
Continuity mistake: There are only two ambulance attendants who take the pregnant gunshot victim to the vehicle, but en route we see two attendants in the front seat - driver and passenger, and a third attendant is in the back with John and the victim. Then when they reach Rampart, the attendant that was in the back with John has vanished and he's the one who opens the back door from the outside. As an aside, in the ambulance, when John talks to Rampart about fetal heart tones, we see the attendant is actually mucking around with the IV drip.
Daisy's Pick Blind Date - S4-E7
Continuity mistake: When John shows Chet the card with the address that Daisy gave him, Chet quickly takes John's pen to write the address, and when John grabs his pen back he quickly and unsuccessfully tries to put the pen back in his shirt pocket, but in the next shot the pen's in his pocket.
Daisy's Pick Blind Date - S4-E7
Continuity mistake: When John and Roy are with the little boy in respiratory arrest, while John uses the Ambu bag his watch reads 12:15, then he informs Rampart that they have O2 on the boy and goes back to the Ambu bag, and now his watch reads 12:25, though it's only been a minute.
Continuity mistake: When Station 51 is dispatched to 'vehicle accident with injuries', Roy is in the locker room still getting into his uniform with his shirt untucked and belt undone when re runs into the apparatus bay, but in the next overhead shot Roy's uniform is on properly.
Continuity mistake: When Chet and John are by the sink talking about Chet's appearance on the news, in the reflection we can see the three lockers behind Chet, and in the next shot the door of the fourth locker is wide open, blocking the third locker, and we can see that it's open because of the poster that's taped to the inside of the fourth locker's door.
Continuity mistake: After loading the officer with the gunshot wound onto the ambulance, en route to Rampart when Johnny is checking the wound, Johnny's watch reads 11:10, but when he's adjusting the mask and the resuscitator regulator, his watch reads 11:55.
Continuity mistake: After the sniper throws the rifle out the window, Captain Stanley gives the orders over the HT to Engine 12, Truck 23 and Engine 23, and the next few shots of the rigs are from previous episodes including 3x7, "Promotion", when Roy and John rescue the security guard at the structure fire.
Continuity mistake: When John is in the lion's pit with the injured photographer, as he's loading her into the stokes his watch reads 3:40, but after they lift the stokes, when he's on the Biophone with Rampart his watch reads 12:15.
Continuity mistake: At the start, when Chet tacks the notices up on the bulletin board, the papers are tacked to the board differently between the closeups and wide shots.
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.