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.
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.
Continuity mistake: When "Mr Bridges" attacks Jim at Jim's parents home, after Mark kills "Mr Bridges" look at his left arm. (He's wearing a watch on the left wrist.) There is not a single bit of blood and no bite wound. A few shots later, there is lots of blood and a very large bite wound.
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.
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.
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: When Jim learns that the women are going to be forced to become sexual slaves, he barges into the room where they are at and screaming "We have no time, come on!" In the shot when they are physically leaving the room, Selena has her infamous machete in her hand while exiting. When they are in the hall ways running before all three are ambushed by the soldiers, the machete is gone from Selena's hand.