Natalie Cassidy accidentally revealed an EastEnders secret and lots of viewers didn't even realise.
The blunder was exposed when Sonia Fowler (who is played by Natalie) went to open the front door for the police officers who questioned Martin Fowler about missing cars.
As Sonia got off the sofa to answer the front door, the camera follows her and accidentally exposes the set of the BBC soap.
You can clearly see behind the living room wall that there's another wooden wall with a piece of paper that reads 'do not set and strike'.
Check out: next week's EastEnders spoilers - Martin Fowler is in DANGER
EastEnders: Martin Fowler Is Left In Danger - slider
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The week begins with Martin feeling the pressure to keep his work with Ben a secret. However when it gets too much he finally decides to open up to Kush Kazemi.
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Kush suggests they confront Ben but when they do, he doesn't back down. Martin has had enough and decides to come up with a sneaky plan…
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Martin later confides in Jack Branning about a 'friend' in trouble but is annoyed by his response. A suspicious Jack then asks Sonia about her ex-husband, but she manages to cover for Martin again.
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The next day Martin promises Bex Fowler that he'll spend the afternoon with her, but his plans are ruined when Ben tells him he needs to do another job.
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After Tubbs is arrested, he ends up in custody. As a result Martin asks Ben to help out with the job instead – but what is he up to?
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At the end of the week Martin thinks everything with Ben is over but Phil's son goes to extreme lengths to prove that no one messes with him. Before long, Martin is left in terrible danger.
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Meanwhile Louise and Keanu are stunned when Lisa confesses she wants them to move to Portugal and it quickly becomes clear that Keanu isn't keen on the idea.
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Louise tries to convince her boyfriend that she owes it to Mel – who is like a second mum to her - but she's unaware that Lisa feels gutted after overhearing their conversation.
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Jay Brown plays a fun day out with Lola and Lexi Pearce but he has to change his plans when he gets a new booking at work. Jay and Callum Highway are amazed at how big the funeral is going to be.
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However Jay is stunned when he realises the funeral is for Terry Bates – the man responsible for his dad Jase's death.
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Callum is shocked when is dawns on him how much Jay hates him. He decides to ask Ben to help out while Lola comforts Jay.
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When Billy overhears the traumatic day Jay has had he comforts him and the two men have an emotional heart to heart. How will Jay cope with organising his nemesis' funeral?
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Elsewhere on the Square when Billy spots how unwell Honey looks, he's quick to show his concern. However she brushes him off.
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Habiba Ahmed is buzzing to tell Adam Bateman that Arshad Ahmed knows everything – but he's left feeling conflicted.
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Honey is surprised by Adam's behaviour towards Mariam and Arshad and urges him to sort it out. However things take an awkward turn when he buys them tickets to visit India – Arshad sees red.
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Chantelle Atkins is over the moon when Denise Fox asks her to cover at the salon. However when Gray accidentally ends up at the salon he's furious to see his wife at work.
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Chantelle is surprised when she arrives at The Vic and sees everyone there but it soon dawns on her that her husband is angry at her for lying.
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Whitney is devastated when her stall is vandalised but Leo is around and eager to help her out. He's then left annoyed when he realises Callum might get in the way of getting close to Whit.
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He decides to sets himself a mission to ruin Callum's reputation and manages to stumble across something… when he spots Whitney's ex in The Vic he's begins to ask him about his time in the army.
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When Whitney arrives in The Vic she spots a file on Leo's laptop and it has Callum's name on it. Curious, she has a look at it and is left devastated...
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Callum warns Leo to stay away from Whitney but the newbie completely ignores him and continues to charm her.
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Over to the Slater household, Jean receives a mystery parcel and it's a video message from Daniel. On the clip he urges her to seize the day and be more honest with everyone. Unfortunately she takes his advice literally and it ends in a disaster.
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Karen Taylor asks Chantelle and Bernadette Taylor to help try and make things right with Bailey Baker following their recent drama.
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Stuart struggles with his new job working for Kathy and it's not long before Ian Beale tries to embarrass him. Stuart doesn't take it to heart and Kathy is left impressed with his effort.
A few viewers spotted the mishap and poked fun at it on Twitter with one person writing, "Seems a bit of the set wanted to say hi 👋 #EastEnders".
Someone said, "Anyone else notice the back of that set 😂 'do not set and strike' #EastEnders".
A third commented, "We hate to point out fails but. EastEnders camera crew flopped tonight. #EastEnders".
Another fan noticed a slight blunder when Ben and Kheerat Panesar were texting about the missing car; despite their conversation supposedly take place over a few days, all the messages appeared to be sent within minutes of each other.
The viewer tweeted, "Did you notice Ben’s messages. All sent today within a few minutes of each other even though they were sent over different days. Weird thing to notice I know, but things like that just jump out at me".
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This isn't the first time EastEnders has seemingly made a mistake; they suffered a major blunder during their Christmas Day episode that saw Kat Moon discover Alfie was the father of Cherry Slater's baby.
Viewers also spotted an error with Ruby Allen's tragic storyline and fans were left in hysterics following Stuart Highway's awkward gaffe.
Earlier this year Coronation Street also appeared to make an epic blunder with Maria Connorand it's not just soaps because over the summer Love Island viewers spotted a gaffe following claims that the reality show is 'staged'.