Continuity mistake: When Roy finds Bonnie in the back seat of the wrecked car, Paula's luggage flips itself around and upright between shots.
Visible crew/equipment: At the scene of Paula's traffic accident, when Captain Hammer stands in Engine 51's cab and tells Marco to get the reel line, the reflection of equipment and set lighting are visible in the chrome surface of driver's side spotlight.
Continuity mistake: When Squad 51 is dispatched to the heart attack, when Roy opens the apparatus bay door John and Bonnie run underneath, and we can see that Engine 51 is not parked in the bay, but in the exterior shot of the squad pulling out the engine is in the bay.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy