The first time that Brant and Sandra sat outside in front of a small fire drinking wine, when he said, "Let's go inside", they got up and left the fire going - along with the blanket they had been using to keep warm - and went into the house. A few days later when they ate the fish dinner outside at a small fire in the same place as before, he said he would be in after putting the fire out. He should have put it out the first time too since it's dangerous to leave a fire burning in the forest.
After Sandra injured her foot right after her backpack went missing, Brant told her he had put his truck keys in it so they were now missing also. When she ran outside to find her backpack after Brant had taken care of her foot injury, he caught her and said, "We'll go back out tomorrow to look for your keys". He obviously meant to say "We'll go back out tomorrow to look for your backpack."