While Buddy and Abby are making love the watch on her wrist disappears and reappears.
When Abby and Buddy are in Buddy's office lobby (waiting to meet Jim for the first time), Abby's jacket collar is alternately in and out between shots.
Position of logo on the Diet Coke can when Buddy and Abby are eating at their first meeting. Also at his office when they are celebrating closing the deal.
The amount of people on the beach when Buddy gets up off the couch to answer the door when Abby shows up.
Buddy's sandwich during the meal after Abby clinches the deal.