During the rehearsal dinner, Dwight selects a single french fry from the little girl's plate beside him. When the camera angle changes to look over Dwight's shoulder, he is shown to be holding two fries. When the angle switches back to looking at Dwight, he is again holding a single fry, which he then takes a bite of.
At the rehearsal dinner, Pam's grandmother tells Pam, "I wasn't sure about your branch of the family when I heard about your parent's divorce." This makes no sense. The grandmother is either Pam's mother's mother or her father's mother, so there is no separate branch of the family that Pam could belong to that wouldn't also include the grandmother.