Deliberate mistake: In the point of view of the Hispanic cop, he is being lead away by a secret service (SS) guy when the cop hears an explosion, he punches the secret service man but before the SS guy can react, the second explosion goes off. In all the other points of view, the first explosion goes off and there is 30-40 seconds of a break before the second explosion goes off. (Its clear the director needed the cop to have the distraction of the first explosion to attempt to get away, but in order for the cop to escape he had the second explosion go off seconds after).
Deliberate mistake: There are several large security mistakes that were obviously added to the film to move the plot forward. The takeover of "Control" would not happen that way. The Secret Service keeps it in a secret off site location which not even the security detail knows. This location is in some kind of very remote bunker to prevent what happens in the movie. Secondly, when the threat is identified and the switch to the double is made, the President would have been moved to a secure bunker created for the purpose until the threat was dealt with.
Trivia: There were several Secret Service consultants on this film to give realism to the action. However, they were unhappy with the final product as it seemed that the kidnappers were able to get to the President without all that much trouble, even if they did have an insider.