Perhaps someone can clear this up for me as I would hope this isn't simply a blatant error on the part of the show's creators. This has to do with the timing of the Rapture as evidenced by Grace's story in the previous episode.
In these last two episodes, the show has made it clear that the Rapture occurred on October 14th in the United States, but on October 15th in Australia, as Australia is 14 hours ahead of the U.S. on the other side of the International Date Line. And every indication has been that the Rapture happened simultaneously around the world. So, in the first year of the show, it was determined that the Rapture happened at 2:34pm in Mapleton, NY, where Kevin, Jr. was doing his girlfriend in a cheap motel, IIRC, and wife Laurie was having an ultrasound, the time and date noted on the ultrasound display. The girlfriend and the baby both disappeared.
In Grace's casual accounting of that day, she was at the store when the Rapture happened, she knew what it was immediately, and her 5 children, confused and scared when her husband disappeared in front of them, took off into the Outback in search of Grace. By the time she got home, the children were gone, where she simply (hopefully?) assumed they had disappeared along with the 2%. So, if the Rapture occurred simultaneously around the world, it would have been 4:34am in Australia. At that time of the morning, no regular store is going to be open for business, no normal person is going to be traveling miles away to do their regular shopping, and the entire family should be in their beds fast asleep, or perhaps just rising to prepare for the daily chores of an Australian ranch.
So . . . what is wrong with this picture?