At the start the friends share a drink of Mead, a popular drink among pagans, which is wine made from honey rather than from grapes, however they incorrectly refer to it as moonshine, which is home-made whiskey with concentrations above 50% alcohol by volume.
If Jenna, Renee and Ian were trapped in a hot sauna for hours as the temperature rises. They wouldn't be able to speak. Their throats would crack under the heat or the lack of air.
It wouldn't make sense when Ian makes the steamer explode and kills him and Renee and Jenna end up surviving.