Warning: spoilers are ahead for Volume 1 of Stranger Things Season 5, consisting of four episodes and available streaming now with a Netflix subscription.

The final season of Stranger Things roared to its best opening week ever — and the second-biggest premiere for any Netflix original series.

After Netflix released volume one of "Stranger Things’" fifth and final season, fans noticed a mistake in a flashback scene involving Will Byers (Noah Schnapp) and Jonathan Byers (Charlie Heaton).

So far, the running favorites to bite the dust are Will Byers ( Noah Schnapp) and Eleven. I honestly couldn’t see either happening, but the Stranger Things fan community is certain that someone from the core group won’t make it out alive.

The actress, now 21, was 12 years old when she first played Eleven in the first season of 'Stranger Things' in 2016

Here's a breakdown of how the "Stranger Things" characters' and actors' ages differ in Season 5, including Holly Wheeler, Will Byers, and Eleven.

Cara Buono has seen Karen Wheeler go through a lot over the course of Stranger Things. She unwittingly harbored a fugitive science experiment in her basement. She flirted with a hot, teenage lifeguard. She sported more stellar 1980s hairstyles than there are seasons of the Netflix mega-hit series.

Stranger Things Season 5 Part 2 is set to release right after Christmas, and while the rest of the story of Netflix’s hit show is a mystery, we already know how one project will serve as a key to understanding more about the show.