The chalk mark that Oleg leaves on the postal box is not in the same place when Philip sees it later. It is several inches lower and shaped differently.
Paige is supposedly waiting in her car near the Naval Observatory but the building is #55. Washington, DC is built on a grid with the Capitol in the center. #55 would be in the same block as the Capitol. The address of the Naval Observatory is 3450 Massachusetts Avenue, 34 blocks away from the Capitol. Clearly these scenes were not shot in DC.