In the second series Joe refers to Melanie's previous boyfriend as being "shameless" for the way he dumped her. This is an in- joke about former co star James McAvoy (who played Mel's boyfriend in season 1) who had left the show to star in the hit Channel 4 series Shameless.
When Phil and Nige's radio goes off and you hear someone saying phonetic alphabet words, it always spells out a swear word.
Caroline Aherne originally intended to co- write (and possibly guest star) in the show with Craig Cash but dropped out of the project for personal reasons. Phil Mealy subsequently came on board to co write and star with Cash.