Agnes Skinner is actually a nice old lady in this episode. This was before the creators could establish her as a mean woman. The DVD commentary justifies this change by stating that Bart's cherry-bomb prank is what turned Agnes Skinner cruel and bitter.
Bart has a pet frog in this episode and in an early scene he says "Ahh, the life of a frog, that's the life for me." "Frog" is a crude derogatory slang for Frenchman.
The two evil French wine makers, Cesar and Ugolin, are named after the villains of the classic French novels "Jean de Florette" and "Manon of the Spring" by Marcel Pagnol.
When Ugolin drives Bart to the Chateau Maison, the scenery they pass by are actually famous French paintings. Specifically, they are Bassin aux nympheas by Monet; Champ de ble aux corbeaux by Van Gogh; Le Reve by Rousseau; and Dejeuner sur l'herbe by Manet.
They used real Albanian in the scene where Adil says goodbye to his family, and they tried to get the actual language right at Sam Simon's instigation. They also used real French in the scenes of Bart in France.