Visible crew/equipment: When Brackett and Early are in Rampart's staff lounge discussing J.P. Dumont, Brackett agrees to let Early use his charm in the case, and when Early stands up an actor's small T-mark is visible on the floor, where Brackett was standing moments earlier.
Visible crew/equipment: When John and Roy are tunneling through to the little girl trapped in the hole, they're in the second larger hole that has been shored up on all sides with wood (to keep it from collapsing), but when Roy points the chrome flashlight down the lateral hole Johnny's digging in, we can see in its reflection that the fourth wall doesn't exist, where the camera and lights are located.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy