Visible crew/equipment: After the two guys fill the fish tank with water, when they walk out of Brackett's office Dixie walks in, and as she comments that the tank is classy, the actor's tape mark is visible at her feet, in front of Brackett's desk.
Visible crew/equipment: When the dispatcher drops tones for the trapped victim of a traffic accident, just after we hear Captain Stanley say, "KMG365," we can see movement between the front passenger and driver seats of Engine 51, precisely where the camera is. Captain Stanley is still at the radio base station and Mike hasn't opened the door yet.
Continuity mistake: When Johnny and Roy are with the heart transplant patient who is having chest pains, after they contact Rampart, in the wide shots Johnny has the stethoscope around his neck, but in his closeups the stethoscope is gone.
Other mistake: At the end of the episode, when 51's guys are in the kitchen waiting to see the "terrific idea", in the closeup John presses the tape recorder's third white button to play it, and we hear the dispatcher's voice, but in the next shot we continue to hear the dispatcher saying, "1305 Overland Ave, apt C, cross street, Pacific..." despite the fact that we can see all the white buttons are now up, none are actually depressed.
Other mistake: Brackett has Johnny and Roy in his office to listen to recordings on two cassette tapes - the first of 51's transmission with Rampart, and the second of 49's transmission with Pediatric Clinic. Brackett plays the first tape, pops it out and then plays the second tape. The problem is that when Brackett puts the first cassette tape back in the player, it's been rewound, even though Brackett never actually rewound the tape.
Visible crew/equipment: After Captain Stanley and Roy get the trucker out of the wrecked cab, when Stanley takes his pulse, the outlines of the lav mic transmitter and wire is visible on the back of his shirt.
Visible crew/equipment: When Gage and DeSoto are driving away from Rampart, discussing DeSoto's possible purchase of a new house, dispatch calls about a traffic accident. In this exterior closeup shot of Squad 51, the reflection of the camera's flatbed vehicle is visible on Squad 51's red surface.
Visible crew/equipment: When Gage and DeSoto are stuck cleaning the squad again before The Inspection, Captain Stanley walks in and the actor's T-mark is visible on the floor just before he steps on it. Additionally, when Stanley walks away, and Chet catches up to him, another T-mark is visible on the floor near the doorway.
Other mistake: When Early and Morton are examining Johnny, Early points out Johnny's torso as he says, "Mike, you see this bruise?" but the subtitles read, "Frank, you see this bruise?" A couple of minutes later the subtitles get Mike's name right. Subtitles from Universal Studios 2010 DVD.
The Lighter-Than-Air Man - S5-E8
Visible crew/equipment: When Crockett leaves Medford's room with the glass that Medford drank from, there's a mirror over the sink, and in the mirror's reflection we can see the camera's moving shadow on the wall, right beside Crockett's reflection.
Continuity mistake: When Johnny is being examined by Dr. Early and Dr. Morton, Roy is in the treatment room with them, and he's not wearing a watch, but when Roy steps into the hallway and speaks to Chet he's suddenly wearing a watch.
Other mistake: When the dispatcher calls for Squad 51 about an unknown rescue, Roy almost closes the squad's hood on Johnny's head, and when Captain Stanley responds the usual KMG365 with the hand mic, we can see that the mic's cord is dangling down, not even plugged into the base.
Visible crew/equipment: When the dispatcher drops tones for the 'possible heart attack', just as we hear Captain Stanley respond, "KMG365," we can see movement between Engine 51's front driver and passenger seats, where the camera is located. Captain Stanley is still at the radio base station and Mike hasn't opened the door yet.
Above and Beyond... Nearly - S5-E20
Other mistake: After Dixie gets the call from the dental clinic about the possible MI, she and Brackett take the elevator located at the nurses' station and head up to the dental clinic on the third floor. Problem is that the ER is only a 2-storey building, so that is quite impossible.
Other mistake: When the woman from the salon is brought into the treatment room she's unconscious, but as they transfer her from the ambulance stretcher to the hospital gurney, she lifts her left arm from under the stretcher bar and then also positions it on the gurney.
Other mistake: While Johnny and Roy are with the possible heart attack, they've patched her in for the EKG, and in the base station room Brackett looks at the EKG strip and the unit's monitor, then it cuts to a closeup of the Datascope monitor, even though the Datascope is not actually in the ER's base station room.
The Tycoons - S5-E23
Visible crew/equipment: When Squad 51 is dispatched to the baby with difficulty breathing, in the wide shot when the squad pulls into the driveway and heads to the front of the house, the cameraman steps out of the shadows on the right side of screen and walks toward the squad (then it cuts to the footage he was shooting), and in the next shot as the moving camera closes in on the squad in front of it, the cameraman's shadow becomes visible on the tree and house.
Pressure 165 - S5-E7
Continuity mistake: While Johnny and the doctor are in the pressurized chamber with the diver, the guy outside the chamber tells them that they're at 165 and vetting, as he holds the mic up to his mouth with his left hand, but when it cuts to the interior shot, the mic is held up in his right hand.
Visible crew/equipment: After Chet is brought to the ER, Gage goes to the nurses' station. When Brackett opens the door and walks out of the base station booth, the actor's T-mark is visible on the floor behind him.
Visible crew/equipment: When Brackett's helicopter takes off the filming helicopter can be seen through the window. (00:03:45)
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.