Factual error: When you first see Sam he is supposed to be in America, but when you see out of the window as he is leaving, you can see the Gherkin building in London. He is actually in the Lloyd's Building, but to add to the illusion of being in America, he is picked up by a Yellow Cab.
Factual error: When Troy calls to Gabriela from the rooftop, the clock on the school's facade reads about 7:46, but the sun is almost directly overhead. There's no way it's quarter to eight in the morning.