When Julia's co-worker brings her a coffee to try out from his new coffee machine, he places it on her desk. The shot changes to him a few seconds later. When back to her, the coffee cup is turned 180 degrees - the handle is on the other side, the computer mouse is moved, and a stack of papers near her planner is moved. She did not move all of these things in those few seconds because she is holding some papers that she was reading when he walked into her office.