Toward the end of the movie, the South Portico of the White House is shown with the semi-circular balcony in place. That balcony was not added until the following century. President Truman had it installed during his term in office. It is still referred to as "The Truman Balcony".
Abraham Lincoln tells his men to shoot or slice the zombie's heads off or slit their throats, however Abraham himself slices one in half, and numerous men shoot their waists and that effect still kills them.