According to Virginia, Burt was 17 when she was 15, but on Burt's drivers license it says he is born on 06-08-1971. In an earlier episode Maw-Maw says that she quit smoking in 1971 when Virginia was born, contradicting them being of different ages.
When the doorbell rings Burt gets up from his chair to answer the door, when they cut back to Hope Burt's arm is in the background despite having gotten up already.