When Dean and Rory are talking after the town meeting and he's collecting the chairs, the microphone of the lectern appears and disappears between shots.
In an earlier episode, Rory states that she only gets her diploma holder at graduation. However, the graduates received scrolls of paper with a ribbon tied around them. It appears to be the actual diploma without a holder.
When Paris & Rory each change their tassels they do so incorrectly. Tassels are worn on right initially and then moved to the left during commencement. Paris & Rory move theirs from left to right. The headmaster's tassel is also on the wrong side.