Other mistake: When dispatch drops tones for the fire at Graymar Plaza, we see Engine 8 rolling out of the apparatus bay and heading down the street, but the problem here is that this footage of Engine 8 is from season 5, episode "Equipment", when Johnny was at Station 8 doing overtime, and we can actually see Johnny sitting there on Engine 8 as it rolls by.
Continuity mistake: When Charlie asks Dave how Sue is, Charlie has an oxygen mask on with the elastic around his head, but after Dave tells Charlie that Sue's fine and that Johnny's got her on O2, in the wideshot as Dave walks away the oxygen mask has vanished from around his head.
Continuity mistake: When Johnny tells Sue that Charlie's injury means paid vacation, Johnny is wearing his turnout gear and the coat has long sleeves, but in the closeup when he places the oxygen mask on Sue's face, the arms we see are bare.
Visible crew/equipment: When Evelyn and her husband pull up in front of Graymar Plaza, while they're talking in the car, in the shots facing Evelyn the reflection of crew members standing beside the car, on the driver's side, is visible on the building's glass doors.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy