That's literally my point. It is also a heath risk. The last show I did for them had a ton of ln2 and co2 and the cast had to be briefed on how to react in emergencies. And it had a big air-handling system and automatic doors directly to the outside.
The problem might be that if you add a lot of carbon dioxide or nitrogen to enclosed space...often, you would need to cycle in fresh air just as frequently. There is a lot of wind in that scene. But I'd be surprised if they're connected to an external exhaust.