While watching a football match together, Veronica (Cate Blanchett) tells to the "Tattooed Boy" ('Colin Farrell') that "once she met Eric Cantona" (famous football player from the '90s). Blanchett and Cantona worked together in Elizabeth (1998).
The Irish Film Censor, who passed the film with a 15PG (now defunct, but equal to 15A) certificate, acknowledged on the official Film Censor website, that had this film been fiction, or of any other plot source than it was, it would probably have received an 18 certificate.
When Traynor meets with Veronica on a pier in Dublin, he parks his car right behind Veronica's car, between two small pillars. When their meeting is over, Veronica drives away, which should be impossible because the exit off the pier is completely blocked by Traynor's car and the pillars.
During the epilogue, it is claimed that in an emergency Parliament session, the Government altered the Constitution. This is inaccurate for two reasons. Firstly, no such amendment of the Constitution occurred. Secondly, when an amendment is made, the Government alone does not have the authority to enact it: it may only propose such amendments to the people, in the form of a referendum.
Martin Cahill: [genially but menacingly]
Ah Jamey, Jamey, Jamey. You're an awful man, d'you know that? What did you have to go and shoot your mouth off to the Gards about me for? Did you think I wouldn't find out it was you? You know, I was thinking about killing you. And then I thought to myself, you know, sure, people get killed every day - and nobody gives a shite. So I've decided I'm going to have to hurt you a bit.