In the scene where Hugh proposes to Lisa, Lisa is sitting and she is barefoot. In the next scene when she is standing, her shoes are on.
The bug zapper that catches the flag on fire disappears in between shots.
When Doris and Lisa are speaking "ye olde English", they are making the very common error of (mis)pronouncing the definite article "ye" the same way as the pronoun "ye". In print, "ye" substituted for the word "the" but it was still pronounced "the" or "thee". Only the pronoun (the plural of "you"), was pronounced "yee".
While in England, Hugh uses the American spelling "honor" in his proposal to Lisa. The UK English spelling is "honour".
There is a shot of Maude Flanders at Lisa's wedding. She dies in season 11.