Faith Kent who plays Harvey's grandmother wasn't available for the filming of the wedding scene. Her part was filmed separately and then digitally added in.
Anthony Head and David Walliams had initially rehearsed that Sebastian and the Prime Minister should give each other a peck on the cheek. Head was completely taken by surprise when Walliams launched in at him with a full-on snog.
The whole Dafydd sketch was cut completely for the BBC1 transmission as it contains all sorts of graphic sexual terminology.
When this episode aired on BBC1, the photographs that the two middle-class ladies share of all the penises were pixellated, though they were all seen in its original BBC Three timeslot.
That's actually a stuntman playing a woman in the wheelchair that Andy sends careering down the park.