The car featured in the chase scene is a 2008 Bentley Continental GT Speed. Bentley does not participate in product placement, so the film's producers purchased three of the cars for approximately $150,000. One car was mistakenly driven into a gorge; the second was used for the lion's share of the stunt shots. The filmmakers were astonished at how durable the car was despite the punishment it took; by the time filming concluded, the car only needed a cosmetic refit. Its frame and engine were all intact.

The APC vehicles were manufactured with real steel plating and armor plated glass windscreens so that actors and stunt people could interact with them authentically. They took four or five weeks to design and ten weeks to build. Two were manufactured, and every piece of them was custom made. There was talk of buying similar vehicles that were being decommissioned, but it turned out to be cheaper to build their own from scratch.

Despite having many dangerous choreographed stunts, only two went wrong. A motorcycle rider was dragged when he meant to roll safely aside. He was not injured. Another was the man whom Sol punches in the face on the train platform; on a second take of the scene, the stuntman's nose was broken.

Though the film takes place in London and Scotland, most of principal photography was done in South Africa. The last scene shot on the continent before moving to the UK was the lengthy car chase with the Bentley crashing through the bus.

Two DDS soldiers sent into Scotland are named "Miller" and "Carpenter". George Miller directed the "Mad Max" trilogy and John Carpenter directed Escape from New York (1981) and Escape from L.A. (1996), all heavily influential to this film.

Alexander Siddig, playing the British PM, is the real-life nephew of Malcolm McDowell, playing a leading figure among the Scots in this picture.

When Sinclair and her troops first go over the wall into Glasgow, and explore the deserted streets right before they're attacked, the scene pays homage to James Cameron's Aliens (1986). Both sets of troops ride around in an APC (Armoured Personnel Carrier) and they even get similar lines of dialogue when checking for a possible ambush, like "Check those corners."

The film was made into a haunted house at Universal's "Halloween Horror Nights" in Orlando Florida.

The junction scene uses about 700 extras, most of them Afrikaners.

The assault weapons used by the DDS troopers are (modified) Vektor CR-21 bullpup assault rifles, a product of South Africa, the major filming location of the movie.

The opening and closing title sequences are written using the 'Albertus' font, a direct nod to the influence of John Carpenter who uses the same font in all of his movies.

There is a variety of helicopters used throughout the movie: The helicopter on which Eden is flown out of the quarantine zone at the beginning of the movie is a "Bell UH-1". The helicopter on which Eden flies from London to the quarantine zone is an "Agusta a119". The "gunship" helicopter that picks up Eden at the end of the movie is an "Aerospatiale SA.321 Super Frelon". The helicopter that Nelson uses after receiving the disc from Eden at the end of the movie is a "Bell/Boeing CH-47 Chinook".

The ship at the beginning attacks squad Rhona Mitra / Eden Sinclair called "Pervyj Raz" which means "First time" it is written in azbuka on the side of the ship.

MyAnna Buring, Nora-Jane Noone, and Craig Conway all worked together previously in The Descent (2005)

Scottish Screen contributed 300,000 pounds towards the film's budget.

The character Canaris was probably named after the German spy master during WW2. While most of his duties were in line with Offical Nazi party line, he was known to run some operations for his own purposes.

Since some of the filming took place in South Africa, the registration numbers on the helicopters read "ZS-...". While the helicopter used to pick Eden at the end of the movie wears this registration visibly on its tail, the helicopter on which Eden flies from London to the quarantine zone discretely wears it on its belly while showing a fictive number on its sides.

Rhona Mitra plays a character who as a child lost her right eye by getting shot by a stray bullet, Emma Cleasby who plays her mother at the beginning was in the horror movie, Dog Soldiers (2002) which was also written and directed by Neil Marshall, in which Cleasbys character a werewolf, gets shot in the right eye (whilst transforming) but it doesn't kill her.

The brand of cigarettes that Bob Hoskins and Rhona Mitra are smoking near the beginning of the film is "Collapsed Lung".

The PM's name John Hatcher may be a nod to two of Britain's former Prime Ministers: John Major and Margaret Thatcher.

Chris Robsons character dies the same way, his character died in Dog Soldiers (2002) by going down fighting.

Sean Pertwee's characters demise is somewhat similar, to his characters death in Dog Soldiers (2002) both involving fire.