Family Ties - S6-E16
Revealing mistake: When the fire is started in the patient's room, which is caused by liquid shorting out the clock radio, at the end of the hallway we can see through the window's open shades and the view right outside the window is quite pretty, but in all of the exterior shots of Rampart there is no such view on any of its sides. It's a matte painting.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy