Spoiler alert: This story discusses details of the series finale of “Game of Thrones.”

Forty-three minutes into Sunday’s “Game of Thrones” series finale, Queen Daenerys was dead, Drogon turned the Iron Throne to melted metal and someone left a plastic water bottle in King’s Landing.

Viewers spotted the non-medieval container hiding inside the King’s Landing amphitheater behind a boot worn by Samwell Tarly, who was set on resolving the problems, and future, of Westeros.

(Some fans claimed they saw two during the episode.)

The water bottle represented a final blunder in a season inundated with errors — three weeks ago the Battle of Winterfell was plagued with darkness, and then there was the disposable coffee cup left on set.

Once again, HBO’s oversight swamped social media feeds.

“THE WATER BOTTLE,” one viewer tweeted. “THIS IS NOT EVEN FUNNY ANYMORE.”

Another GoT fan wrote, “So water bottles are a common thing in Westeros.”

HBO has neither returned The Post’s request for comment nor put out a statement (or tweet) about the gaffe.

Some fans felt Sunday’s episode, aptly titled “The Iron Throne,” represented a final flaw in a too-rushed, poorly written eighth and final season.

Now that winter finally came, the critics say it’s an unfortunate way for HBO’s Emmy-winning series to go out.

As one viewer wrote, “They aren’t even trying at this point.”

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