Other mistake: When John and Roy treat the 12 year old boy in anaphylactic shock, Early states, "Start IV D5W, 1 milligram epinephrin IV push," and John confirms the order. Then after giving Rampart a new set of vitals which are poor, Early orders, "Add 50 milligrams Benadryl IV push." But when John confirms that order he only says, "1 milligram epinephrine IV push," (which is the earlier order) and Early actually okays John's incorrect repeat of the order, even though John did not confirm the order of "50 milligrams Benadryl."
Other mistake: After Station 51 is dispatched to the 'vehicle accident with injuries', in the exterior shot as the squad and engine roll out, we can see the real Station 127's vehicle is still parked inside the apparatus bay, near the rear bay door.
Other mistake: When Squad 51 is dispatched to the liquor store shooting, en route they are almost hit by a driver who passed a stop sign at the intersection. This is the same footage from season 2, episode 13 "Drivers", when the squad is almost hit by a car while responding to a football injury.
Other mistake: At the scene of the vehicle accident, with a raging fire going on, the Chief communicates over the HT with Copter 10, and when Copter 10 arrives and makes the water drop, it is actually Copter 14 we see in all the shots.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy