Jonny Lee Miller offered to shave his head to look older, but Danny Boyle insisted that Sick Boy retain his iconic blond hair.
Danny Boyle has credited David Bowie with helping to be able to use various hit songs in the original movie inexpensively because he had ties with Lou Reed and Iggy Pop, and helped Boyle out because he was a fan of Petits meurtres entre amis (1994). For his own little personal tribute to him following his death, Boyle decided to shoot a moment where Renton goes through his record collection and finds a couple of Bowie's albums. (In the novels, Renton is a fan of Bowie).
Robert Carlyle kept away from his family in Glasgow while filming because he became so much like Begbie.
Although this sequel had a substantially bigger budget than its low-budget predecessor, the director and cast all took an equal but lower salary than they were offered, to keep things in perspective. They were offered a share in prospective profits, though.
In Trainspotting (1996), Jonny Lee Miller's Scottish accent was his own. He tested his accuracy in a Glasgow bar stating something along the lines of 'if I could wing it there I was ok'. For this film, however he had a dialect coach, something that Ewan McGregor jokingly put down to Miller not being drunk this time round.