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
The film's British title, "Green Street", comes from the street in London where the Boleyn Ground (formerly Upton Park) is located.
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.
The film's working title was "The Yank".
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).
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.
Cameo: [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.
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.