Revealing mistake: When Frank ties the bedsheets together to the sink, he ends up pulling the basin off the pedestal. Surely that would cause a flood, but we don't see any water come out at all.
Revealing mistake: When Frank and Betty move the wardrobe, the walls wobble.
Revealing mistake: Before Frank pulls the mat from under the wardrobe and tears it, you can see the mat is already torn and placed back together.
Revealing mistake: When Betty goes into labour in the night and goes downstairs with her suitcase, she tries opening the front door. You can see it moving with her pulling. And then when Frank goes to climb out of the window to follow the key, he climbs onto the sink, which almost rolls away, which reveals the fakery of the set.
Jessica's First Christmas - S2-E7
Revealing mistake: When the second piece of scenery falls on Frank, it has a tear halfway down and a hole in it that Frank's head goes through. A few seconds earlier, these weren't there. Maybe they were put there to make sure Frank's head went through, or else this is the second take.
Jessica's First Christmas - S2-E7
Revealing mistake: At the final rehearsal for the church nativity play when Betty first comes on stage with baby Jessica wrapped up in a blanket and places her in the manger, it is obvious that Jessica is actually a doll.
Jessica's First Christmas - S2-E7
Revealing mistake: The walls of Frank and Betty's bedroom wobble when the door is shut.
Revealing mistake: When Frank is the pixie in Santa's grotto, a young boy fires something at Frank from his catapult. Although Frank reacts as being hit, the boy doesn't actually fire anything at all.
Revealing mistake: When the bottle of wine explodes in the cupboard, just after Frank has shaken it, you can see a pushrod inside the cupoboard pushing the top up.
Revealing mistake: Just before the runaway mini goes into the horsebox you can see the stunt man dressed all in black laying down inside the car steering it.
Revealing mistake: While Frank is taking his driving test, he and Mr. Hayes are wearing standard road safety belts in the car. But when the car is in the sea after crashing through the fence, both the occupants are wearing motor racing type safety harness obviously fitted for the stunt.
Revealing mistake: When Frank drives his car into the sea, he and Mr. Hayes escape through the sunroof. You can see that the actor playing Mr. Hayes has been changed to a stuntman as the hairstyle has changed and he is wearing a lighter coloured suit.
Revealing mistake: When the flying saucer crashes down onto the wishing well, it is obvious that the Father Christmas in the saucer is a dummy.
Moving House - S3-E1
Revealing mistake: At the beginning when Frank is directing the vans, we see that one gets its windscreen broken by a ladder from another van. However, the glass breaks just before the ladder touches it.
Wendy House - S3-E2
Revealing mistake: When Frank is talking to the postman at his front door, it's so obvious it's a studio set. The background seen outside the front door is painted scenery.