When they show Hallie running in the street, she is barefoot. Then in the next shot she is wearing platform shoes.
At the end of the movie when the father is driving Duncan home the seats in the car are tan leather. After the crash the seats are black leather and it is an older style BMW.
When the secret service agent finds out that the president is in jail Duncans mom is facing him but in the next scene she is facing the opposite way.
When Duncan is asking his dad if he can take the car, his dad tells him to take the station wagon, and hands him a ring with only one key on it. Duncan takes the company car, but both cars wouldn't use the same key.
At the end of the movie, when Duncan and Hallie are going out for a second date, the camera pull back to show Secret Service SUVs and a helicopter following Duncan's car. The buildings are skyscrapers, which are much too tall to be Washington DC, as building codes for the District provide that no building may be taller than the Capitol, which is only 287.5 feet tall. (The Washington Monument is the only exception.)
The traffic signals in Washington DC do not have yellow backplates around the lights. Yellow backplates are unique to Canada.
At the end of the movie, when they are driving off to go on their date, right before the secret service turns the corner. At the four way stop, drivers are supposed to stop, but Duncan didn't stop at the stop sign.