The amount of flour that lands on Jesse and Michelle changes between shots. Most noticeably, a large amount of it disappears from Michelle's hair shortly after Jesse joins in.
When Michelle walks into her classroom, her backpack disappears from her shoulder between shots.
While talking about his grand father Jesse says he needs to make the arrangements. Michelle later comes home from school. It's been all day and Jesse is just now talking about making the arrangements.
During the flour-throwing, one of the times Papouli says, "Opa!" his mouth doesn't move.