While escaping the military-guarded location, Jim is wearing a green shirt and his hands are bound. After scaling the wall and dropping to the other side, his shirt has been caught on the razor wire atop the wall, but his hands are still bound.
When the camera pulls back to show Manchester aflame, a row of flashing lights is visible in the distance. It's the police keeping traffic back so that the road looks empty. About 2 seconds later, a car drives by in the distance.
The blockade is supposed to be situated North East of Manchester. Yet during the scene when Jim escapes back to it, the signs read Blackpool and Fleetwood, and also shows signs for Lancaster and the Lake District. These signs are only seen on the M6, running to the West of Manchester.
Frank drives his taxi through the Blackwall Tunnel because "it's the most direct route to the other side of the river." They start on the north side of the river and head north toward Manchester. Going through the Blackwall Tunnel would actually take them south.
Rage can spread from human to animal or animal to human, by biting, or infected blood landing in the victims mouth, eyes, or nose. The movie has no infected dogs or birds of prey. The virus may require a host closely related to humans, like the chimps from which the outbreak originally began. This is reinforced when the film shows uninfected horses.
About eleven minutes in, someone walks up a distant sidewalk. Since Jim is calling out for someone, that person would've heard Jim, or Jim would've seen him. Clearly, the person is not part of the movie.
When the Jeep returns to the mansion after picking up Jim, Selena, and Hannah from the roadblock, two soldiers open the gate to let the Jeep onto the grounds. The black soldier is Private Mailer, the soldier tied up in the backyard. In the DVD commentary, Danny Boyle said he was so impressed with Marvin Campbell in the few small scenes he'd shot that he decided to cast Campbell as Mailer. All of Campbell's previous scenes were deleted, except the shot of him opening the gate.
After Jim stabs Pvt. Jones with a bayonet attached to a rifle, Jones is shown falling forward onto the rifle. This would've caused further damage and possibly kill Jones in the process. However, seconds later, when Major West walks up to Jones to comfort him, not only is Jones still alive, but laying on his back and the rifle nowhere to be seen.
When Frank has been shot and the soldiers are approaching his
body, you can see a cameraman lying down at the right of the screen in front of a concrete block. He's clearly visible for about three seconds.