Visible crew/equipment: When Squad 51 is dispatched to 'man unconscious possible heart attack', while en route, two shots after Roy says "It's gonna be a long run," the reflection of the squad is visible on windows they drive past, and we can see the reflection of a crew member who's standing on the back of the moving squad. Slow motion is not necessary to see this. However, if you're into slo-mo you can catch it again later, when John and Roy head to the traffic accident victim.
Revealing mistake: During the rescue at the jail, while Roy tries to get a safety belt around the prisoner's waist, the man freaks out, then grabs Roy and they both swing out on Roy's safety line. When the camera pans a bit too far to the left, we can see the edge of the fake "sky" screen on the left, behind the building's replica set used for closeups.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy