Continuity mistake: Herman dumps coins on the map and as they explain how to use them, the spread of coins changes and there is a pile of coins that wasn't there before. (00:26:36)
Winterfest - S10-E9
Deliberate mistake: Even though it's supposed to be Christmas time, the trees are lush with green leaves, no breath is visible when the actors talk and in the background you can see people wearing shorts and T-shirts.
Winterfest - S10-E9
Factual error: There are trees full of green leaves, no visible breath from the actors and people in the background wearing shorts and T-shirts despite the story taking place at Christmas time.
Answer: Internet sources give many reasons why firefighters do this, but in regards to your question, it's probably because opening walls and ceilings creates better ventilation which allows heat and smoke to escape, giving firefighters better visibility and lowering the temperature.
raywest ★