Continuity mistake: At the beginning we see Jim walking across the Westminster bridge towards the Parliament Buildings. Big Ben shows that it is around 8:10. Then the camera moves way back to a wide shot of the bridge, and we see that (according to Big Ben) it is suddenly 25 minutes later.
Visible crew/equipment: Watch the scene where Frank gets killed. In the last shot of this scene, we see a soldier standing over the dead body. Keep an eye on the right side of the screen as the camera slowly moves away and you should see one of the cameras and a cameraman on the ground next to a large metal object.
Continuity mistake: When Jim and the other two characters are making their way to Jim's parents house, they are seen on the Docklands Light Railway track going towards a place called Island Gardens. The next shot shows them at a station called East India which is completely the other direction to where they were going down the track. Obviously, only users of the railway would pick up on such error though.
Factual error: In the scene on the motorway where we see Manchester burning, the road signs are for the A421 and A507, which are at M1 junction 13 near Milton Keynes and nowhere near Manchester.
Continuity mistake: In the final scene where Jim, Selena, and Hannah are waving down the jet flying overhead, Selena is wearing a green sweater/coat over two layers of red shirts. It cuts away and returns to her suddenly lacking the green sweater. She was seen jumping and waving already with it on, so it's not like it fell off from movement.
Continuity mistake: There is a scene early in the film where the garage explodes. A view from high up shows the explosion. Later in the film when Jim and Frank are on the rooftop, you get practically the same view but look at the area where the explosion was earlier. Everything is perfectly normal and there is NO sign of any explosion.
Continuity mistake: After Frank has been killed, when everyone is being taken to the soldiers' mansion, note the person on the right opening the gate, does he look familiar? Well he should because in a few scenes later he has suddenly become the infected private Mailer chained up. (This is due to a late cast change).
Continuity mistake: In the scene where the survivors are driving up to the 42 barricade (near Manchester) there is a shot from inside the taxi. In this shot the windscreen wipers are on. Yet in the next shot, from outside the taxi, from ontop of the barricade, the windscreen wipers are not on.
Revealing mistake: When Jim is walking across the Westminster bridge and shouts "Hello?" for the first time, in the next shot you can see a blob on the bridge (right of picture). This is all that's left of a car going across the bridge, that wasn't painted out completely.
Continuity mistake: When Jim is wandering the deserted streets after waking up from his coma, there is one overhead shot of Jim walking down the street, towards a silver car. When it then cuts to a closer shot a red double decker bus appears underneath the "Landmark Advertising" billboard. A small white van/truck has appeared in front of a medium-sized white lorry, and the position of the silver car parked in the centre of the traffic lights grid changes between subsequent shots. Also between these and following shots, the position of the trash littering the streets differs.
Revealing mistake: After the soldiers execute their spiritual comrade, Jim takes cover in the field of dead bodies nearby as the executioners run off to search for him. The body right in front of Jim is breathing, as his chest is moving up and down.
Factual error: After they leave Jim's parents' house Jim and Selena are seen walking through Canary Wharf, but they're coming from the wrong direction. The Docklands Light Railway tracks that they use to cross the river are in front of them and their base (in Canary Wharf Tube station) is even further in front of them. Why did they cross back over the river and then walk away from the safety of their base?