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.
Despite dealing with a "killer virus" that's managed to get an entire country quarantined, the soldiers at the blockade are wearing nothing to protect themselves from infection - just gas masks, which will help against toxic gases but do next to nothing against something as small as a virus - and even have exposed skin, such as their hands and necks. Full biohazard suits might be a bit much to expect but surely the joins in their fatigues should be sealed with tape and all skin would be covered, at least.
In the opening scene at the England/Scotland border it is 9.17pm on June 20th but it is pitch dark. This is almost midsummer and it would be broad daylight at this time.
Doomsday is based on a screenplay by British screenwriter Neil Marshall, who also directed the film.
Q
What are the differences between the theatrical version and the unrated version?
A
The film's theatrical cut was rated R by the MPAA. Later, an unrated version was released on DVD and Blu-ray, adding more story to the film.
A detailed comparison between the theatrical version and the unrated version can be found here.
Q
What is 'Doomsday' about?
A
Thirty years after Britain successfully walled off Scotland to contain the spread of the Reaper virus, a particularly lethal virus that has infected millions, England is devastated to find that the virus has popped up again in London. Consequently, Major Eden Sinclair (Rhona Mitra) of the Department of Domestic Security is asked to lead a team of operatives into the quarantine zone to find medical researcher, Dr. Marcus Kane (Malcolm McDowell), who was last known to be working on a cure...that is, if they can survive the survivors who have taken over Scotland.