Stranger Things viewers were stunned after a major wardrobe blunder seemingly slipped under the radar.

The smash-hit Netflix series has been releasing its final season in batches – with the finale set to land on New Year’s Day.

Ahead of the show wrapping up for good, eagle-eyed fans were left asking ‘How did Netflix not notice this?’ after spotting a gaffe.

The blink-and-you’ll-miss-it moment featured Holly Wheeler (Nell Fisher), who became stuck in Vecna’s (Jamie Campbell Bower) Pain Tree.

As Holly tried to break free from this predicament, viewers noticed she appeared to be wearing a long-sleeve Under Armour t-shirt.

The popular sportswear brand launched in 1996, while Stranger Things’ current storylines take place nine years earlier, in 1987.

Eagle-eyed Stranger Things fans were left shocked after spotting a glaring wardrobe blunder in a scene – the Under Armour logo

One viewer wrote on X: ‘Ts p**sed me off even more how did they not notice this.’

Another asked: ‘How does something like that even slip by?’

However, a third viewer defended the series, remarking: ‘A mistake could happen anywhere, there is no need to dwell on it.’

It comes as the latest volume of episodes became available on Boxing Day – setting the stage for the final episode.

Fans were quick to point out the gaffe on social media and aired their complaints

Meanwhile, showrunners Ross and Matt Duffer set the record straight on a ‘confusing’ moment featuring Jonathan Byers and Nancy Wheeler.

Viewers saw the fan-favourite couple share a tense and emotional moment in a dramatic, near-death scene.

Jonathan – portrayed by Charlie Heaton – pulled out an engagement ring in front of Nancy, who is played by Natalia Dyer.

The moment initially seemed like a proposal, however, the show’s co-creators clarified that the couple are not engaged and explained their intent with the scene.

Off-screen, the actors who play Nancy and Jonathan are still a couple in real life, but their on-screen characters ended up breaking up during the romantic ‘un-proposal’ scene, the showrunners explained.

The pair are trapped inside the Hawkins lab in the Upside Down when a toxic, poisonous substance begins melting everything in the room.

Elsewhere, Stranger Things showrunners clarified a confusing scene featuring characters Jonathan and Nancy (Pictured, played by Charlie Heaton and Natalia Dyer)

It’s then Nancy tells Jonathan that she hates The Clash. Then, he confesses that he doesn’t like to read her articles and finally admits that he never applied to Emerson.

At that moment, he pulls out an engagement ring from his pocket and extends a proposal-like offer.

‘I figure that I have screwed up enough with you that it’d be nice to get something right for once, in the end. Nancy Wheeler, will you not marry me?’

She accepts his ‘un-proposal’ before telling him she loves him and they kiss. After they part, they see the substance had hardened around them and realize they’re still alive.

Brothers Ross and Matt revealed Nancy and Jonathan’s fate in an interview with People published on Thursday.

‘That’s a breakup,’ Matt told the outlet as he clarified the intent of the scene. ‘They are broken up.’

Matt said that he and Ross wrote that scene after having known for ‘a while’ that the couple were going to break up.

‘It’s hard to recall when exactly that idea came, but I think us – and the writers – all felt that Nancy needed to end up on her own and be independent and have an opportunity to find herself,’ he said.

Stranger Things is available to stream on Netflix now.