Hmm, this had the potential to be good but fails. 8 different people witness an assassination attempt on the American president whilst he's in Spain. The same scene is shown over and over again from their viewpoint, each time revealing a bit more of the plot.
The same story telling technique was used in Rashomon by Kurosawa over 50 years ago, so nothing new there, although given the stagnant nature of mainstream film-making it does stand out. Rewinding the story to just before the explosion helps to keep the intensity and stops it becoming a stale trick.
There are plenty of twists, and even more holes e.g. How did the little girl make it to the underpass so quickly, why having killed hundreds of people would the terrorists want to avoid someone who steps out in front of their get away, but the most obvious mistake being how Forrest Whittaker was able to keep up with 2 Secret Service agents in pursuing one of the bad guys.