Continuity mistake: When Jeff Clarke comes by the firehouse, Hermann wants to hug him but Clarke says "I don't really like people touching me." But throughout season 2 Clarke has hugged other fellow firefigthers (Cruz among others) with no problem.
Factual error: In the scene at O'Hara airport the paramedics meetup with a TSA officer. The TSA officer has a gun as a part of his uniform. TSA officers do not carry firearms. In addition, the CBP officer in the scene does not have on a proper CBP uniform. The CBP officer uniform has rank epaulets and officer has no epaulets, and the CBP uniform doesn't have a bar tie clip and the gun belt buckle is brass not stainless metal. (00:42:00)
Escape Route - S9-E8
Continuity mistake: When Casey is in Molly's bar, Stella places a beer down in front of him. The level and amount of foam changes several times throughout the scene before Casey brings the glass to his lips.
Apologies Are Dangerous - S3-E4
Continuity mistake: When driving to their first call that shift (guy stuck between cars), Truck 81 is seen arriving at the scene while it should be still being repaired. When they arrive back at the firehouse, the truck they drive carries the number of the exchange truck they've got (E-..).
Continuity mistake: Casey and Seagar run down the stairs leading to the parking garage. Seagar passes the 15th floor twice (large sign on the wall).
Continuity mistake: Brett enters the abandoned factory twice when she is searching for the missing girl.
Visible crew/equipment: A man trying to escape rams the front end of his smaller vehicle into the right front end of the ambulance, causing significant damage. But, there is no damage to the front end of the vehicle. It's visible in the scene that the smaller vehicle is on a ramp, so it's high enough to be able to crash into the right front fender and grill of the ambulance. (00:52:07)
Continuity mistake: When Ritter pulls up to the overpass, the car's lights are on. They are off in the next shot when he exits the car and on again in the next shot as he walks away from it.
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.
Where the Collapse Started - S4-E22
Visible crew/equipment: After the paramedic locates the injured firefighter, the shot cuts to the outside and the camera operator's shoulder can be seen in the lower left of the shot.
Continuity mistake: While at the Firehouse and talking about Dawson getting Candidate EMT Tara "tanked", they have pancakes and sausage and as Otis sits, his sausage is on top of his pancakes and then when Casey walks up the sausage is cut up on the side. Then when it goes back to Otis the sausage reappears back on top of the pancakes, untouched. (00:28:28)
Other mistake: Captain Casey has Lieutenant pins on his uniform instead of Captain pins. (00:31:00)
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)
Revealing mistake: In the scene on the roof when Severide is removing the helicopter door with a spreader, there is no hydraulic pump or hoses attached, just the bare tool. When he sits the tool down you see this. So the spreader would not be working at all.
Character mistake: In the first call to a working structure fire Severide proceeded to head towards the basement from the middle level by walking down stairs but falls through. His first mistake was not checking the stairs with the halligan as any firefighter is taught, to check if they are sturdy. And last but definitely not least no firefighter should ever walk down stairs, especially wooden framed ones if they are on fire.
Continuity mistake: Chief Boden is in his dress uniform and his award ribbons above his right pocket are hanging down. There is an emergency and he orders the firefighters to mount up to depart the firehouse. They all leave in a hurry, and when Chief Boden arrives on the scene his ribbons are no longer hanging from his jacket, but intact and straight above his right pocket. (00:41:00 - 00:43:00)
Continuity mistake: Casey and Kelly are on the roof smoking cigars when a man runs up carrying his daughter yelling for help. Both Casey and Kelly put down their cigars and are next seen sliding down a ladder with black gloves on. They were not smoking cigars wearing gloves, and wouldn't have time to put them on to get off the roof as fast as they did. (00:21:00)
Continuity mistake: When Brett and Dawson go rescue the two climbers, at the very beginning you can see a long shot of the group where the victim is laying with her legs and arms straight, while in the rest of the scene she lies there haphazardly in consequence of the fall. (00:09:45)
Continuity mistake: When Dawson and the police detective are knocking the door of a suspect a neighbor is coming out to sidewalk and the snow is piled high along the sidewalk and parked cars. The next scene shows the ambulance and fire engine on the road with no trace of any snow. (00:44:00 - 00:47:00)
Continuity mistake: At the hospital, when Cruz talks to Herrmann while he still has the oxygen mask on, Herrmann's hand keeps switching between clutching the mask on his face and resting at his side. (00:38:45)
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 ★