Other mistake: When Squad 51 is dispatched to "possible heart attack" the address is "91st and Formosa" (the 'Black Tower' can be see behind the Chevron sign when the squad rolls up), and later when they're dispatched to "person caught in mailbox" the address is "Beverly Blvd and Main." What's funny is that the two incident scenes are filmed at the same corner of the intersection, with Universal's 'Black Tower' nearby. Have a look.
Other mistake: When Roy and Johnny are working on the squad's engine, while Johnny's lying on the mechanic's creeper, Roy is holding a spray can with white tape wrapped around the top of the can, so the brand name would not be visible.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy