Visible crew/equipment: After Station 51 is dispatched to the bomb threat, when the squad and engine pull into the alley, just as Roy stops the squad, the reflection of the cameraman/camera are visible in the spotlight's chrome surface.
Visible crew/equipment: When Station 51 is dispatched to a man trapped at World Picture Studios, just after they pass the studio's gate, in the moving shot from the left side of Squad 51, the reflection of the cameraman is visible on the lightbar atop the squad's roof.
Visible crew/equipment: After the fake eye exam 51's guys are sitting around the kitchen table, and when Chet tells them that he was sitting in the front row at the movies, there are moving shadows at the bottom, right corner of the screen, which do not belong to the guys.
Visible crew/equipment: When Roy and Johnny enter stage 3 to search for both Vic and the bear, just after Johnny and Roy split up, as the camera moves forward in Johnny's direction, the moving shadow of the cameraman/camera are visible on the filing drawers, to the left.
Visible crew/equipment: After Squad 51 is dispatched to a man injured at the movie studio, just as they reach the studio, in the shot from the back of the squad, the reflection of cameraman is visible on the lightbar atop the squad.
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.
Transition - S4-E15
Visible crew/equipment: At the start of the episode, when Captain Stanley leans over to hang up the telephone and walks out of his office, the outlines of the lavalier mic transmitter and wire are visible on the back, left side of his shirt.
Visible crew/equipment: When John and Roy help the driver out of the overturned armored truck, the bulging outline of the mic transmitter is visible on the left side of the driver's shirt, and when Roy's arm is around the man's waist, Roy even puts his palm over the mic transmitter as he bends to pickup the man's gun.
Camera Bug - S4-E10
Visible crew/equipment: At the start of the episode, when Johnny is taking photos of Roy in the locker room, the actor's tape mark is visible on the floor below the bench, where Johnny stands when he shows Roy the article in the newspaper supplement.
Visible crew/equipment: During the structure fire, after Roy and John climb out onto the ledge and the fire flashes in the exterior shots, the next interior shots we see shows stacked boxes falling as the fire flashes through the doors. The interior shots are from episode 3x7, "Promotion", during the structure fire, after the security guard is taken down the ladder. We can even see a crew member's hand pushing a lower box which causes them all to fall.
Visible crew/equipment: After the fire at the Kiddytime Toy Factory, when Roy is in the ambulance and Johnny closes its back doors, the location set lighting is reflected on the glass of the ambulance doors.
Visible crew/equipment: When the dispatcher calls for Station 51 to respond to the "structure fire at the Kiddytime Toy Factory," while Captain Stanley is at the radio receiver base station, the reflection of the camera equipment is visible on the back of the squad's cab as it trucks left.
Visible crew/equipment: At the scene of the swaying sign accident, when Roy and Johnny get the gear out of the squad the outlines of the mic transmitters are visible on the left side of Johnny's shirt and right side of Roy's. Once they're on the roof both of the mic transmitters' outlines are on the right sides of their shirts, and later when Roy and Gil are pulled up onto the roof, the bulging outline is visible again at Roy's right side.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy