Revealing mistake: The guys turn on the TV and discover the channels don't work. When Rik changes the channels, he leans in front of the TV hiding the screen. This is because the 'channel' never changes at all - it's just a picture stuck onto the TV. You can see this when the camera rotates around, just before the screen goes out of view, behind Rik.
Revealing mistake: Near the start, when Vyvyan sticks his hand through the wall to swear at Rick, you can see where the holes from previous takes have been papered and painted over.
Revealing mistake: When Neil is about to blow up the kettle, watch as he plugs it in. The power point moves a bit.
Answer: Madness.
jle