Deliberate mistake: After Johnny's and Captain Stone's efforts, when the construction site's cardiac arrest is wheeled into Rampart, the problem is twofold; First, we hear Roy's voice saying, "Full arrest, number four," even though Roy is not actually on this run (that line is from S4xE21 "Back-Up", when they wheel the cardiac arrest into treatment 1, after defibbing him atop Engine 51). And second, the attendant pulling the stretcher changes, and the EKG monitor lying on the patient is the old blue Datascope 850 from earlier seasons (this shot is from S4xE7 "Daisy's Pick", the hypothermic victim - note his wrapped foot!), whereas at the construction site and when he's wheeled into the treatment room, the EKG monitor is the newer white Datascope M/D2.
Pressure 165 - S5-E7
Deliberate mistake: When Roy and Johnny are on the Coast Guard helicopter, approaching Catalina Island with the injured diver, there is a closeup shot of them looking out the windows, which is a flipped shot - note the backwards paramedic patch on the right sleeve, instead of being on the left sleeve.
Deliberate mistake: When Johnny and Roy are on the Coast Guard copter, responding to 'victim down at cliffs at Catalina Island', there are four closeups of the guys looking out the windows which are flipped shots - note their uniforms are backwards, the paramedic patches are on their right sleeves instead of their left.
Deliberate mistake: After the fireworks begin exploding at the warehouse fire, when Captain Stanley and Roy are helping Willy out, they are knocked to the ground by an explosion, and in two of the following exterior shots the large sign that reads "Kiddytime Toy Co" is visible. This shot is from season 4, episode "The Screenwriter", when the guys respond to the fire at the toy factory that also made fireworks.
Deliberate mistake: When Roy and Johnny are on Copter 10, just after dispatch tells them that the run is cancelled, there is a shot of Copter 10 turning around which is a flipped shot - note the backwards 10 on the tail.
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.