Continuity mistake: When Kath, Kim, Kel and Sharon are eating dinner at the restaurant, the food on their plates and the position of their plates changes.
Visible crew/equipment: Literally seconds into the episode, when they are at the club eating dinner, the tip of the boom mike is visible.
Plot hole: When Kel is giving a toast to Kath at the restaurant, he says that he has been married to Kath for a month. In Episode 8, Series 1 "The Wedding", their wedding was held on 18th September yet it is New Year's Eve now. That's not a month, that's at least three.