The song 'For a Friend', which is heard playing over the end credits, was actually written for the real Mark Ashton. It was written and performed by The Communards, whose members Jimmy Somerville and Richard Coles were both friends of Mark.
While there had been more than 1,000 coal mines in the UK during the first half of the 20th century, by 1984 there were only 173 still operating.
Although Mark's political affiliation was not mentioned in the film possibly to avoid alienating viewers, a communist flag can be seen hanging from his apartment wall in the opening sequence. In the movie, he can be seen wearing red star pins on his jacket lapels, and he also gets "commie" shouted at him when going on a stage at a gay bar.
In interviews to promote the film, Bill Nighy said that the emancipation of gay men and women in the UK in the post-Margaret Thatcher years was one of the greatest things to have happened in his lifetime.
Some of the actual people depicted in the movie make cameo appearances in the Westminster Bridge scene: Reggie Blennerhassett and Ray Aller (played by Chris Overton and Joshua Hill), Gethin Roberts (played by Andrew Scott), Gethin's Mum (played by Olwen Medi), Mike Jackson (played by Joe Gilgun) and Ray Goodspeed (not directly portrayed in the movie but a leading light in LGSM).