Pics from a person on the other site, looks like releasing on Dec 5th (or the 28th, it's unclear), but a target employee put it out early by mistake, and this fellow bought one...(sorry, probably too big of pics..)
I was literally about to post this same exact information, you beat me to it, haha. The poor guy went in an Old Navy changing room and opened it because people were accusing him of making a fake, and suggesting he get's perma-banned LMFAO!!
That's for the Blu-ray Discs. All Ultra HD's have to be region free. I'm not sure why they have that text printed on there, it is the same as the Blu-ray text though so perhaps it's mandatory they put it on.
The product page for the Stranger Things Blu says "Only in stores" on the international site so you cannot put it into basket.
However, you can search for "Stranger Things" and put it into basket from the search results. Then you can check out normally.