When we first see her character she’s clearly eating a croissant. The camera moves away and, seconds later, moves back to see that she’s now eating half a pancake instead.
One more two-second cut, and the pancake is magically whole. When shooting a scene with food, all edible items need to be replaced at the beginning of every take.
Because people eat differently from one take to the next, continuity errors like these are born and are difficult to spot. One of the most famous scenes in the movie is where Richard Gere’s character presents Julia with a diamond necklace and then snaps the box shut on her fingers causing her to laugh hysterically.
This was not part of the script and was actually improvised by Gere. However, the director loved it so much he decided to leave it in the final edit. The necklace used in the opera scene was actually worth a staggering $250 million. It even came with its own armed bodyguard sent by the jewellery store to discourage any crew members from taking it home as a souvenir.