At 1:04': the needle is pushed through the skin at 45 degrees way too far: it will have pierced the vein, gone through it and into the muscle (the veins he is after are very superficial).
At 39': an intramuscular injection should never be done in the neck as it can perforate a major vein, a carotid artery, the trachea (windpipe) or esophagus (food pipe) but rather in the deltoid (shoulder) or the gluteal muscles (buttocks) or quadriceps (thigh muscles).
A news report says, "all three men were gunned down between 6pm and 12pm last night."
It should be between 6pm and 12am. 12pm is noon.
In the rave scene, set in 1988.. there are multiple posters advertising "Happy Hardcore". Happy Hardcore wasn't around in 1988, it wasn't until between 1991-1993 that rave music evolved in to Happy Hardcore.
During the fight with Man United (set in 1982), a D-registration police car pulls up to stop the fight. D-reg cars were manufactured in 1986-87.
In the rave scene, set in 1988 (again), you can spot someone wearing a 2007 season Gio-Goi T-shirt in the crowd.
When the ICF are on the bus to Man Utd game (5 mins in to film) they are spraying cans of alcohol and you can see a can of Magners (black can introduced in 2007).
Near the start of the film at the match set in the 70s/80s when Bill Gardner throws the Bovril in the man's face you can see a West Ham flag. The club crest on the flag wasn't launched until 1999.
At 1:47: Jack is not wearing gloves and yet he is shutting the 4WD doors with his hands, leaving finger prints that would be picked by the police.
At 47': the barman is speaking out loud on the telephone right in the direction of the Turkish characters he should have been more discreet to make sure he was not overheard.