No, I can't really go back to the hotel. I have read on another spoiler fan site that TAR#8 was rumored to be going to Pompey's Pillar (a Lewis & Clark site) near Billings, the CM Russell Museum in Great Falls and apparently Havre, MT (close to Canadian border). Apparently there was something about "purple sidewalk squares" and these are ventilation grates for an underground mall in Havre. These locations were mentioned back in July.
Perhaps the crew is filming extra footage of areas they already filmed this summer. Although, that does not explain the boats on the Missouri River in Fort Benton on Friday. By the way, Fort Benton is between Great Falls and Havre.
I have lived in Montana for a number of years now, and I have to say, if anything happened here this summer, word would have leaked out. Great Falls, although with almost 60,000 residents is like a small town. Nothing stays secret.