Charlie Hunnam wanted Tommy Flanagan, to play the role of his older brother, even going to a bar for three nights that he knew Flanangan frequented with a script in hand for him to read. They would later co-star on 'Sons of Anarchy'.

Creator of the critically acclaimed FX series Sons of Anarchy (2008) Kurt Sutter has claimed he had his eye on Charlie Hunnam for the lead role of Jax Teller after seeing this film.

To research his role, Charlie Hunnam met with real members of the ICF (the Inter City Firm, the name given to West Ham's former hardcore firm of football hooligans).

West Ham were approached by the film-makers who wanted to shoot scenes at their Upton Park ground. As they were under the impression that the film was celebrating the glorious game and its fanatical supporters, they agreed. Once they realized the film's true take on the subject (after filming had taken place), they disassociated themselves from the project.

Lexi Alexander originally wanted to cast Jake Gyllenhaal as Matt Buckner.

The actors playing the Green Street Hooligans had to work out with the production's trainer for four or five hours every day. The trainer, Pat E. Johnson, had most of the actors throwing up, he was working them so hard. A typical day would involve basic strength and fitness training for about two hours, followed by choreographing of the fight sequences. Rehearsals would take place in the afternoon, and then in the evening they would all go out drinking (which is probably why most of them were throwing up the next day). Elijah Wood was absented from most of this rigorous schedule to emphasize his outsider status.

Terence Jay, who plays Jermey Van Holden, also performs the song 'oneblood' that plays during the final fight scene.

The pub that Matt and the others drink in is actually called The Griffin, and is situated in Braemar Road. Brentford. Home of Brentford FC.

The film's working title was "The Yank".

When Matt goes to his first West Ham game we are told that they are playing Birmingham, when really the game they are watching was West ham playing Gillingham

When hopping off the train at Macclesfield, as they are expected at Manchester and being waited for by the rival firm, it is not actually Macclesfield Station, but Westbury train station, in Wiltshire, a couple hundred miles away.

Was nominated for the William Shatner Golden Groundhog Award for Best Underground Movie. The other nominated films were Mirrormask (2005), Nine Lives (2005), Up for Grabs (2004) and Opie Gets Laid (2005).

A few of the players In the schoolboys football team actually went on to become professional football players, the boy who scores and celebrates with a somersault is Billy Knott, who was a youth player at Chelsea and he also played for Bradford City, he scored the equaliser in the league cup tie against Yorkshire rivals Leeds United and also played in the team that beat Jose Mourinhos Chelsea 4-2 from 2-0 down at Stamford Bridge in the FA Cup in 2015. Blair Turgott is the boy with short dreadlocks, he also played for Bradford City, he was in the team that beat Arsenal in the League Cup at Valley Parade and played in their very famous wins against two more premier league clubs ( Wigan & Aston Villa ) when they reached the English league cup final in 2013.

On the school marker board, during the match announcements, one of the questions concerning Napoleon Bonaparte is "Why was he so short?".

Marc Warren (Steve) and Ross McCall (Dave) both starred in the famous Mini Series "Band of Brothers" by Tom Hanks and Steven Spielberg. Marc Warren played the role of Pvt. Albert Blithe and Ross McCall played Joseph Liebgott, a Jewish Member of Easy Company.

In the hospital, Bouver is igniting his lighter signifying reflection (at what he did) meanwhile Pete is trying to put two halves of a styrofoam cup back together, signifying his struggle to keep the GSE together after they find out Matt studied journalism.

Several lines indicate in the film that Tommy Hatcher and Bovver used to be friends before turning enemies, and that he's got to be careful coming to Millwall. This is because Bovver was a Millwall fan before changing to West Ham.

Tom Hardy was considered for the role of Pete Dunham.

Manchester Station where the opposing firm at waiting for a fight is actually Fenchurch Street station in London

The scenes with players celebrating a West Ham goal features real life West Ham players. You can clearly see Marlon Harewood and Michael Carrick in the celebrations. Carrick had moved to rivals Tottenham Hotepur by the time of the films release. The Tottenham firm are who GSE fight at the very start of the movie.

Cass Pennant: One of the Manchester riot police at the train station. Cass Pennant was one of West Ham United's Inter City Firm's (ICF) leaders and a notorious hooligan in the late '70s.

A pivotal component of the film involved the Major marrying Shannon, a "Yank". In reality, Claire Forlani is actually British.