When Wallace (Sinise) is watching TV after the events in Selma, the gas masks that the Alabama state troopers wear change in between scenes.
When Wallace is about to appear on stage at Harvard, the wide view (possibly actual footage?) shows the curtain opening with a hand up at about chest level and another person ducking out towards the left (of the picture). In the close-up of him though, the hand is much farther down and the second person is not to be seen.
The future Cornelia Wallace is depicted as a small girl on her uncle's shoulders at Jim Folson's inauguration on January 17, 1955. In fact, Cornelia would have been eleven days short of her sixteenth birthday at the time.