I recently watched though all the episodes on DVD (well about 2 months ago) and I noticed 2 HUGE plot holes the show makes along the way, so whilst I'm dropping by these forums today I'll point them out.
1. Carole finds out she's pregnant in the last episode of series 1 when Angie is Brittas's secretary then in Series 2 Julie takes over and Carole says that she did it with a Mystery man (Brittas) at Julie's New Years Eve party. Meaning that party must have either taken place before Julie had been employed as replacement for Angie meaning they all knew her before she had come to work at the centre or the writers just screwed up. (I think the lata)
2. Another total screw up is in the 1994 Christmas episode which is set in the future but flashing back to 'a few weeks after the centre had opened' meaning the timeline from Series 1 is screwed up and features Julie (when it would have still been Angie) but it's also the re-built leisure centre layout from Series 5 when the events are taking back before it burnt down and would have been the original layout.