Visible crew/equipment: When Station 51 is on scene at the vehicle accident in the canyon, after Marco uses a crowbar to free the driver of the station wagon and he pulls the driver out, a crew member standing behind the FX 6-ft wind machine fan (to blow smoke) are visible in the background beside the other overturned car. As an aside, in the previous and following shots that crew member and wind machine fan are in the same spot where Chet and Johnny supposedly are.
Visible crew/equipment: At the liquor store shooting site, when the second gurney is loaded into the ambulance, the outlines of the mic transmitter and wire are visible on the back, left side of Johnny's shirt.
Visible crew/equipment: When the guys are at the scene of the vehicle accident, after Roy asks Captain Stanley and Captain of 69 to assist the man to the top of the hill, the reflection of the array lighting is visible on the side of Engine 51 as Mike works the engine's pump panel.
Visible crew/equipment: When Station 51 is dispatched to a vehicle accident in the canyon, en route there's a shot from the POV of the top of Engine 51, with the dome light in front of the camera, and the reflection of the covered camera, which is mounted on the engine's roof, is visible in the dome light's chrome surface.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy