Continuity mistake: When Four bangs on the table and the silverware is jostled, there's nothing under his arm or by the plate. In the next shot of him a spoon is next to his arm and the plate. And when he is leaving, items on the table change too, such as the position of the glass of water that was next to Tris.
Continuity mistake: Tris overpowers Peter in the testing chamber. After Jeanine says that she has enough guards, Tris pushes him away and turns around. A second later Peter is in the control room with Jeanine, his face already cleaned and without blood.