Factual error: In the standoff between Meat and O2, Meat pulls the trigger to shoot O2 and his gun clicks - it is out of rounds. This is a common mistake: semiautomatic pistols do not re-cock after the last round is fired - the chamber remains open, so the gun will not click if the trigger is pulled again.
Factual error: In the scene where the rocket launcher is fired and blows up the plane, the sound should have been delayed a second or two after the plane exploding.
Factual error: Jasper is implied to live somewhere south/southeast of London, however when Theo meets him at the railway station signs can be seen reading "Alresford", the filming location, which is in Hampshire and too far west to be a plausible meeting place.