Director Jim Sheridan was heavily criticized for fictionalizing much of the story. For example, The Guildford 4 and the Maguire family were tried separately. Joe McAndrew, the IRA man who befriends Gerry Conlon in prison, is entirely fictional. Gerry and Giuseppe Conlon were in different prisons for most of their sentences. Although solicitor Gareth Pierce was instrumental in investigating and preparing Gerry Conlon's case for the High Court of Appeal, she could not present the case in court because she was not a trial barrister. MIchael Mansfield, a barrister and Q.C. (Queens Council) presented the case. Pierce never represented or met Giuseppe Conlon, who died in 1980, nine years before the appeal.
The trivia item below may give away important plot points.
When lawyer Gareth Peirce (Emma Thompson) gets her hands on Gerry Conlon's case files, some of the file folders have writing on their spines. One of the folders has name Crowley written on it. Another "Guildford Four" member, Paddy Armstrong, is played by Mark Sheppard, who would later play Crowley on Supernatural (2005).