The Girl on the Balance Beam - S5-E18
Other mistake: The dispatcher gives the address of "woman trapped on a wire" as "Commercial Studios,1122 Dellini Plaza", and as Engine 51 drives past the front gates, the large sign reads "World Pictures Corp." Additionally, the address of World Pictures Corp is 1731 Carlson, when we see the same footage of Engine 51 driving past the sign in episode "The Exam" in season 6.
The Girl on the Balance Beam - S5-E18
Other mistake: Twice during this episode, when they're dispatched to a "woman trapped on a wire" and also to the "train fire", we see Engine 51 heading out with two firemen standing at the back of the engine, and they are Johnny and Roy. This footage is actually from the episode "The Old Engine" in season 3, when they got the new Ward La France engine for Station 51, and since Roy and Johnny were waiting for the previous shift to return with the squad, Captain Stanley told them to jump on the back and go with them on their first run with the new engine.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
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