Factual error: The flag on the outer left of the square keeps changing between the correct flag for Germany (horizontal black, red, yellow) as seen from the aerial shot when the bomb explodes, and a wrong version (horizontal red, yellow, black) which can be seen when Howard Lewis first accesses the square. (00:34:25)
Factual error: The engine noises coming from the Chevrolet Astra (blue car) are not coming from any engine in that car. Only the Vauxhall and Opel variants of that model got the high performance petrol turbo engines. It's clearly a Chevrolet from the logo on the front and back of the car.
Factual error: The movie was supposed to be in Salamanca, Spain, but was shot in Mexico City and Puebla, Mexico. There are constant landmarks that are easily pointed out if you have ever been to Mexico City. Best example: the metro is that of Mexico City. Salamanca doesn't even have a metro. The square where the president is speaking is actually two different locations. The one shot from above is Salamanca but the one close up is from of a museum in Mexico City. You can easily tell these two apart. The tunnel that the president is taken under so he can get into the hotel secretly is a tunnel under the anthropology museum in Mexico City. The chase scene is shot in the streets of Mexico City and Puebla's main square. The green taxi Beetles that are famous in Mexico City can be seen as well, as can the small buses known as "paseros" that are used as public transportation. There are many others as well. One shot of the chase scene was shot on the street I lived on in Mexico City. I watched the whole thing over a five day period.
Answer: He assumed by the movement of the curtains that there must be someone up there, which of course the Secret Service should have cleared to make sure there was no-one there.
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