This flight check-in page allows you to choose seats from a 'row 34' which is shown in front of all the other rows and with 9 seats.
Is this just for overbooking? What are these seats like?
The plane is an American Airlines MD-80
According to SeatGuru this row doesn't exist. I'd suspect a bug in the booking software, and wouldn't book a seat in this phantom row if I were you :)