According to Christopher Morris, Barry, the Jihadist group leader, was based on a former BNP member who in an attempt to out-knowledge the Asian youths he regularly assaulted, studied the Qur'an and as a result "accidentally converted himself" and became a Muslim.
Following Omar's bomb speech in his living room, you can hear Waj shout "fuck mini babybels". According to an interview with Kayvan Novak, this was completely improvised.
The film had its world premiere at Sundance on January 23rd, 2010. The same day, the UK "terror threat" level was raised to "severe" due to non-specific "chatter".
Look for "If you're reading this, find out what's wrong with you" in the small printed credits. As of October 2010, the poster is available in high resolution on the official UK website.
The last scenes set in London were filmed in Sheffield. The scene in "Kebabish" was filmed at Kebabish on the Wicker, in Sheffield. The other scenes were filmed on the Moor (a shopping area being renovated) and Campo Lane. Also, there are some shots where "For Sale" signs are visible and clearly show that they refer to Sheffield.