Prior to this, Morris spent multiple years researching for the film, conducting interviews with terrorism and religion experts, law enforcement, and British Muslims.
The film grossed £6 million worldwide and received positive reviews from critics, with praise for the screenplay, direction, themes, humour, and cast performances (particularly Ahmed's).
When Omar and Waj travel to an al-Qaeda-affiliated training camp in Pakistan, Barry recruits a fifth member, Hassan, after witnessing him pretending to commit a suicide bombing at a conference.
The training in Pakistan ends in disaster when Omar accidentally destroys part of the camp attempting to shoot down a suspected drone; the pair are forced to flee.
Barry wants to bomb a local mosque as a false flag operation to "radicalise the moderates" and Faisal suggests blowing up a Boots because it sells contraceptives and tampons.
After the group begins production of the explosives, Hassan is left to watch the safehouse as Barry, Waj and Faisal test detonate a small amount of TATP contained in a microwave, using a nearby fireworks show to cover the sound.
Two police snipers receive Omar's description, a man dressed as the Honey Monster, but one of them mistakenly kills a bystander in a Wookiee costume.
Morris spent three years researching the project, speaking to terrorism experts, police, the secret service, and imams, as well as ordinary Muslims, and writing the script in 2007.
[6]Chris Morris explained that Jesse Armstrong and Sam Bain were brought into the project as "experts in the school of male psychology, plus they have technical expertise and experience of comedy dialogue.
He received Morris' attention after writing a song called "Post 9/11 Blues" which he wrote about being detained at Luton Airport after the screening of the docudrama Road to Guantanamo in Berlin.
[7] Morris suggested in a mass email, titled "Funding Mentalism", that fans could contribute between £25 and £100 each to the production costs of the film and would appear as extras in return.
"[18] The UK première took place at the National Media Museum as part of Bradford International Film Festival on 25 March 2010,[19] and was followed by a nationwide release on 7 May.
[20][21] The UK premiere at the National Media Museum in Bradford was followed by a question and answer session with Chris Morris, Jesse Armstrong, Sam Bain, three of the principal actors, and two of the producers.
The site's consensus reads, "Its premise suggests brazenly tasteless humor, but Four Lions is actually a smart, pitch-black comedy that carries the unmistakable ring of truth.
[27] The Daily Telegraph wrote that "[Chris Morris's] evocations of the claustrophobic mundanity of the Muslims' lives, their querulous banter, their flimsily pick 'n' mix approach to the Koran all feel painfully, brilliantly real.
"[28] The Daily Express rated Four Lions four out of five and praised the performances in particular, calling the film "brilliantly cast with all the actors displaying sharp comic timing and both [Riz] Ahmed and [Kayvan] Novak also bringing out the touching humanity of their characters".
[32] Andrew Pulver, also writing for The Guardian, gave the film a more favourable review, stating that "Chris Morris is still the most incendiary figure working in the British entertainment industry".
According to the Official Top 10 UK Film Chart (7–9 May 2010), Four Lions was placed at sixth, behind Iron Man 2, Furry Vengeance, A Nightmare on Elm Street, Hot Tub Time Machine and The Back-up Plan.