When Nessa asks if Baileys has any alcohol in it, the raised front leg of her Welsh Dragon tattoo has rubbed off. In the making of the 2008 Christmas episode Ruth Jones challenges viewers to spot which scene in the series features this error.
Bryns Picasso can be seen with a magmount antenna fitted for a cb unit yet he uses a hand held transceiver which has its own aerial.
On the CB, Nessa says that there's a 4 car pile up on the M4 so take Junction 11 and follow the A48 to Chepstow.
Junction 11 of the M4 is actually in Reading 90 miles east and nowhere near the A48 (its the A33 junction).
Towards the end when Stacey is saying goodbye to Gwen, a boom mic is reflected in the front window of the house.