Geography of London
Certain though I am that this point will have been made before, it bears repeating:
I was interested to see this movie because I live in London and work in a senior role within the House of Commons, so I always derive a certain perverse pleasure in seeing my office get blown up on film, as it frequently is. I don't mind action films either, and despite its flaws I thought this was a reasonable effort at the genre. That said, it had its problems.
One of these was the total impossibility of infiltrating the great swathes of the British emergency services that would have been necessary to pull off the plot of this movie. It couldn't be done, even if the Prime Minister himself were an enemy agent. Before we even start on the security barriers, who on earth would ever volunteer for that mission, and how could they ever be recruited? But aside from defying the laws of common sense, the script-writer also thought fit to defy the laws of physics:
One simply cannot make that plot work on the geography of London as it currently exists. The first problem, which alerted me that things were not all well, was the shot of the the bloodied white rose on the ground just after the President's 'getaway' vehicle got away. This was an apparent reference to the earlier scene just before the German Chancellor was shot outside Buckingham Palace by the Foot Guards (and here it's taking me considerable effort to restrain myself from digressing on the impossibility of replacing an entire company of the Foot Guards with enemy agents), implying it was the same flower, and so the deaths were occurring in the same place. The trouble is, St Paul's Cathedral, where the President actually departed from, is more than three kilometres to the east northeast.
The President then was driven to Somerset House, and made it, which makes sense considering it's only a short 1.3Km away. But then the wheels really start to come off. It was stated they were heading to Standsted Airport, which would have required flying just under 50Km north northeast, at that point on almost a tangent from the Thames, yet for some reason they found themselves flying along the river. Then when they were eventually brought down, it was in the north-east corner of Hyde Park, a direction they had had no business going in.
Last of all, they then expressed the intention to foot it to Standsted, an impossible goal under the circumstances anyway considering it's now more than 50Km away to the north northeast - and yet in their attempt to do so they ended up at Charing Cross Station, about 2.25Km east by south!
So if there was an enemy agent in this film, the best candidate, against all other evidence, would seem to be Gerard Butler. That, or he didn't have a clue where he was going.