Visible crew/equipment: After rescuing the injured man from the burning theater, when Roy and John are on the roof getting the stokes with the victim onto 36's snorkel, we can see a crew member's arm/hand, wearing a white patterned long sleeve shirt, standing at the right side of the screen.
Visible crew/equipment: When Roy and Johnny are with the hypothermic refrigeration engineer, the outlines of the mic transmitter and wire are visible on the back, left side of Johnny's shirt. Note that when Johnny and Roy are in the ambulance with the patient, Johnny is not wearing the lavalier transmitter and wire anymore.
Other mistake: When dispatched to the fire in the theater, the companies called are Station 51, Engine 85, and Station 36, but at the scene of the fire we see Engine 9 roll up and also see firemen with 19 on their helmets. These are shots from previous episodes including 3x7, "Promotion", when Roy and John rescue the security guard at the structure fire.
Other mistake: When Johnny and Roy are in the ice house, there's a closeup of Johnny's arms as he's hosing down the ice and removing it from the hypothermic victim's arm, but it's obvious that the dark hairy arms belong to the stunt double, not to Johnny.
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.
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: While Roy, Johnny, and Cap are in the ice house with the hypothermic victim, there's a closeup of the pipe's frozen shut-off valve in the upright position with an ammonia leak, and the manifold temp/pressure gauges that are hanging from it. Then, when Johnny goes to wrap the rag around the valve it's upside-down, but in the next shot the valve is upright once again, and the manifold gauges are now facing the opposite way.