Revealing mistake: When mini is in the bath at the start of the episode you can see the bandeau she is wearing in the bath when she lays back down in the tub, probably to stop her being exposed.
Berry Scary - S1-E7
Revealing mistake: Blue is walking down a hall with a paddle ball in his hand. He is twirling around the ball and string around the paddle. However it's obvious that the string is somehow just passing through the paddle itself and not going around it. It's especially noticeable when he stops and the string slows down and visibly passes right through the wood of the paddle.
Revealing mistake: While Grandma Dynamite is on the roof sending smoke signals, Sonny is standing in the tree. When Sonny starts laughing we can see the bottom of his jagged clothing is now a mere straight line and his legs have vanished. (00:16:45)
Revealing mistake: The opening scene was shot twice, complete with a rear-end automobile collision in the foreground for both takes. The initial collision destroyed the taillights of the first car and the headlights of the second car and ruptured the second car's radiator on impact, spilling its contents into the street. The production crew attempted to sweep away the debris with a broom before the scene was reshot. If you examine the roadway before the two cars appear in this scene, you will see a prominent splatter on the pavement that has been swept with a broom almost precisely where the cars impact again moments later.
Revealing mistake: When Freeth, Carter and Regan raid the flat, Freeth breaks the door down - the door starts to fall before Freeth hits it.
Revealing mistake: In several episodes throughout the series we see Simon's car driving down a dual carriageway with a blue van and a silver car by the side. This shot is used several times.
A Fistful of Paintballs - S2-E23
Revealing mistake: When Chang is getting blasted with the minigun, the safety pads under his shirt are very noticeable. (His shirt is extremely "puffed out" and you can see the outline of pads.) He's been tied up most of the episode and wasn't wearing pads earlier, so there's no way he was able to get pads on in the meantime.
Disneyland - S3-E22
Revealing mistake: The episode was filmed with real Disneyland visitors. One can constantly see them staring at the camera and/or Disneyland cast members standing with their backs to the actors, monitoring the crowd. This is especially noticeable when the family first arrives and when Mitchell and Cameron talk about Lily's leash: behind the actors, there are long white rope lines supervised by park staff to keep visitors at a distance. Several people can be seen filming the actors or taking pictures with their phones.
And the Rich People Problems - S1-E4
Revealing mistake: When Caroline's dad "calls her" when Caroline puts the phone to her left ear the phone is on the home screen, compared to the screen you should get if there was a call.
Mewtwo VS Shadow the Hedgehog - S3-E6
Revealing mistake: During Shadow's Super Shadow transformation, half of the background becomes a green screen.
Revealing mistake: The woman becomes possessed while the police are attempting to arrest her. She turns her head around and cracks her shoulders so she can walk at them backwards. They did not change her hand positions, so her right hand is where her left should be and vice versa. (00:11:00)
The Real Man - S1-E6
Revealing mistake: Eileen's cell phone is obviously turned off, as the screen is black when she tries to call Shannon and Jodi.
Aunt Bee's Cruise: Part 1 - S1-E15
Revealing mistake: Aunt Bee is traveling on a cruise ship. The "water" in the background is a painted backdrop which is made all the more obvious by the painted whitecaps.
Revealing mistake: When Matthew is sliding backwards because his shoes are icy, just before he falls you can see the board he was on to allow him to move backwards. (00:02:00)
Revealing mistake: Mr Knight shoots Suzie Boreton - after the muzzle flashes and sounds stop the bolt of his MK14 EBR continues to move back and forth as if it's still firing. (00:30:30)
Revealing mistake: Patty Duke's stand-in is visible behind Cathy when the family is in the front hall welcoming their aunt.
Revealing mistake: When the students see themselves in the TV, (which meant that Skidmore was watching them because Chyna had given her a hidden camera) you can see in the TV that there is actually a green screen on the screen and the video is not actually playing, it was just edited in later.
The Return of the Seven (1) - S2-E1
Revealing mistake: When Dennis is picking up Vicky from the hairdressers in the Jag, you can see people standing around watching the filming.
Blue Wants to Play a Song Game - S1-E14
Revealing mistake: After Blue and Steve play the monkeys jumping on the bed game with the sock monkey, when the mail time song plays Steve gets up excitedly and his arm and hand get cut off.
Revealing mistake: It's obvious by his hand movements that Gunner Graham isn't actually playing the piano.
Suggested correction: If I take some random episodes, S7E5 (01:54) or S3E1 (21:51) or S7E1 (13:21), it's either real or at the very least the touch matches the notes in time. This is all on YouTube for easy check-up. S8E2, which centers on him playing something complicated, doesn't show his hands, so avoids a mistake. Glimpses during opening credits are less well-matched over the seasons, but then, that is supposed to be the score only. Claims that it's all very obviously fake just don't seem to ring true.
Suggested correction: I have recently watched the whole run of the series, every single episode, and I do not agree for two reasons. First, there are no close-up shots of hands on the keyboard. Sometimes it's bound to be a recording, for example when the monsoon breaks and the piano is full of water. But that is not a mistake. Second, the show released its own LP record, and actor John Clegg is credited for playing one musical number on that album. So I'm not so sure if he wasn't the real pianist all along. It makes sense that they'd cast someone who could actually play well enough.
If you look carefully, it obvious to any one who plays the keyboard, he's not playing. Also its as plain as the nose on his face that in shots with him playing the accordion, it's a fake.
Of course the accordion is fake - that is just the one episode where they were sent to the front line, so they needed to do something. But I'd very much like to get an episode & time where it's "plain as the nose on his face" please, apart from special situations like in the pouring rain. (I repeat, no-one else is ever credited for the piano, not even on the record album; and it would be strange casting then, since he was always the mediocre pianist from day 1).