With regard to the napkin and the champagne glasses - she prepped the tray with the cabinet door ajar, and when she closed the door, the corner of the napkin got caught in the door, so when she lifted the tray, the napkin was stuck. I caught this and mentioned it to my husband, as I've done this before when I worked in catering, and I also broke a few glasses. When Kate laid the glasses on her tray, all of the napkin corners were folded under, so no extra fabric was hanging over the edge of the tray (and she held the glasses down with her hand for extra safety).
