Other mistake: Bo (obviously an adult), who worked with Kevin, was able to walk into the high school cafeteria and take Phoebe into a hallway to talk without any school personnel seeing him or questioning his presence. (00:30:10)
Continuity mistake: At the school's memorial service for Kevin, Addison was seated in the upper right-hand corner of the auditorium, a few seats from the wall. A view of students in the large mid-section shows them looking toward the upper left-hand corner while he is talking. (Their heads are turned in the wrong direction to be watching him). (00:18:50 - 00:19:13)