The shots in the vent really irk me and kinda show how staged the series is likely to be.
We saw the female (I've already forgot her name) put the vent cover back in place after crawling inside, but then there were shots inside the vent of her face. They obviously sent a camera crew into the house that removed the vent after getting the shot of the cover going back and just shoved a camera in her face because the shots in the vents shows there was no room for a camera to be mounted on the top of the vent. Same goes for all the shots of Caitlyn, especially that bullshit shot of her turning around inside the vent and shouting "are you coming?".
So there was absolutely no chance of them getting caught by unaware housemates, and even if they really were unaware and they did get caught they wouldn't fail them for it because of the camera crew in the house making it super obvious. It was just contrived shit to give Caitlyn immunity so she wouldn't at least be the first evicted, sorry, I mean eliminated since it also looks like they've nixxed the term eviction/evicted.