An unplanned scene
Some of the best scenes in movies are the ones that are totally unplanned and that is exactly what happened with Pretty Woman. The scene where Edward Lewis presents Vivian Ward with a diamond necklace for the opera and then slams the box shut was totally unplanned.
Gere thought up the idea himself and waited for Julia Roberts reaction. Of course, Roberts let out a huge laugh and it was one of the best scenes in the movie.