Other mistake: When the ambulance arrives and they're loading Johnny onto the ambulance, Captain Stanley says, "Okay, Chet, take the squad..." but the subtitles get both characters wrong, it reads that a "Paramedic" says, "Okay, Chip, take the squad..." There is no Chip.
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.
Continuity mistake: At the nurses' station, after Roy tells Brice that Brightweiser will be okay the two of them walk to receiving carrying their gear, with Roy holding the Biophone and defibrillator, but as they head through the doors both the Biophone and defibrillator have each turned around in Roy's hands, and now face the opposite way.
Other mistake: At the construction site, after Johnny administers the epinephrine to the cardiac arrest, 39's paramedic resumes CPR, and when they're lifting the patient onto the stretcher Johnny says, "Stop CPR," but the subtitles read, "Start CPR," which makes no sense since they've been doing CPR all along.
Visible crew/equipment: When Station 51 is dispatched to the possible heart attack, just as Squad 51 is leaving the apparatus bay and passing the exterior glass doors to Captain Stanley's office, the reflection of the location's array lighting is visible on the glass doors.
Visible crew/equipment: After inspecting Davey's Dogs, when John and Roy head to the squad discussing how only a total idiot would buy the stand, the reflection of the location's array lighting is visible on the squad's surface, and the reflection of the camera dolly can be seen on the chrome spotlight.
Visible crew/equipment: During the fire at the chemical plant, a couple of shots after we see Captain Stanley walking between Roy and Chet as they're manning two hoses on the roof, we see a shot of Engine 15 as it heads toward the camera and then drives past it, and the reflection of array lighting is visible on the engine's surface.