Audio problem: In the 9/11/2010 episode there is a scene where Alfie and Roxy have just got back from selling her things to pay for Ronnie's wedding. There is a different audio range from normal speech - Roxy's voice comes across rushed and too loud compared to the other lines she speaks. Also her mouth does not move in sync when she says "So how you feeling about tomorrow, are you nervous?" (00:24:15 - 00:25:00)
Revealing mistake: Episode aired 06/05/2016. Steve (Ronnie's stalker) pulls out a folder of newspaper clippings concerning Ronnie's baby-swap case. It shows up close an "article" which is seemingly legit when reading the first few lines...only to show the same sentence repeatedly, merely the information having been rephrased. Either the Eastenders-verse bears some rather incompetent and careless journalists, or the writers of the soap were simply too much too bone-idle to write up even the most mediocre of articles. (00:28:05)
Continuity mistake: 7th August 2008: before Clare is leaving, the taxi is facing forwards and when Clare is entering the taxi is facing the other way. (00:51:09)
Other mistake: When Lucy is in the cafe watching the mother and her children, the mother repeats the same dialogue.
Continuity mistake: On the episode dating 22nd January 2010, when Peggy is telling Roxy off for firing Tracey, they are in the kitchen. Roxy then turns to walk downstairs, and her ponytail is high and bouncy. Then, two seconds later, when she is visible again, her ponytail is low and messy.
Factual error: When Cindy wanted a hitman to kill Ian she looks in the yellow pages to find one. Surely the police and the makers of the yellow pages would have been alerted if a hitman agency wants to advertise itself in the yellow pages?
Continuity mistake: When Kelly and Zoe are freezing on the Scottish Highlands together against the burnt out minibus, Zoe's lips change colour back and forth through out the scene. It does from hypothermia blue to nice and pink just before Zoe and Kelley kiss.
Visible crew/equipment: The episode where Lisa is running away with Mel. (The episode where Steve dies) There is a scene where Lisa and Mel are panicking at a bus stop, Mel hails a Taxi. When the Taxi stops, you can see the WHOLE crew in the Taxis reflection. Cameraman, soundman, equipment etc.
Factual error: When Barry dies in the Scottish Highlands, Janine has him cremated. However, she manages to get back to Walford in roughly 4 days, no police force would allow for a body to be cremated 4 days after death, especially with an unknown circumstance of death. Also it would look very suspicious that the widow was so keen to get her husband cremated, slowing the police force down even more.
Revealing mistake: Episode Aired 12th December. In the laundrette a shelf had fallen off the wall and Dot Cotton needed someone to fix it. You could see the wall was false, as every time Dot touched the shelf, the wall was wobbling. Later same episode Martin Fowler fixed the shelf he said something like "the wall will fall down before the shelf does" - very true.
Audio problem: In a recent episode where Jane is moving into Ian's place, she accidentally knocks over Ian's daughter's clay vase she made. When you hear the crash, it sounds something like glass shattering on tiles, but it's clay that has fallen on a carpet.
Visible crew/equipment: April 14th 2006: When Phil opens the door to get out of the Range Rover you can see the camera reflected in the door glass.
Audio problem: 30/9/10 Throughout the scene when Stacey and Janine are fighting, you can hear the sound effects of thunder and falling rain but you can not see the rain and no one is getting wet.
Plot hole: Why is it that no-one in the square owns a washing machine. Surely this would mean the launderette would always be crowded.
Continuity mistake: What happened to Alfie's bruises after getting beaten up by Andy's heavie? They disappeared within 2 days, real bruises stay for longer than that.
Continuity mistake: In the episode where Ash has been kicked out by his Dad for having a relationship with Shirley he comes back to pick up his things. He asks if he's ok, his hair is wet and slicked backwards. He then walks into the next room a few seconds later and it's dry and to the side.
Revealing mistake: In an episode when Stacey was in the Minute-Mart and she was begging Patrick and Yolande to give her her job back, a man can be seen standing in the doorway. But when the man looks up and sees the camera, he soon scrams out of the shot.
Revealing mistake: In the legendary episode where Steve Owen dies, the car somehow manages to get flipped over onto its roof. Only a bomb going off would create such an effect, not just the tank going up.
Revealing mistake: 3/6/08: When Dawn is chasing after Keith while pushing Summer (her daughter) in the pushchair, it is obvious that there is no baby in the pushchair, even though she can be heard crying.
Revealing mistake: In the episode where the "young" group of characters leaves for Scotland on New Years Eve, they're supposedly leaving at 7 in the morning, yet the sun is shining high in the sky during a deep winter's day.
Answer: Most likely a mistake by the set designers or it's a recycled set which already had the switch on (they just repaint and add other fittings).
At my workplace there is a two-gang switch with a three-gang switch underneath it, one of which is for the shop lights, the other four have no apparent use.