When Marge says that a judge said that Homer and Bart need to get along, she might be talking about the episode The Parent Rap. However this episode takes place two years ago so it may or may not be true.
The trail where the Simpsons and the Flanders were riding the mules is too narrow for the off-road jeeps to fit through.
In Homer's flashback, Maude Flanders is still alive. There is one scene where he pulls out his touchscreen smartphone and says he has no bars. Maude Flanders died in the year 2000, but no one carried cell phones like the one Homer carried while Maude was alive (the most popular cell phone in 1999 was the Nokia 3310). Due to the Floating Timeline, this makes sense since she died while Bart was 10, Lisa was 8, and Maggie was 1 while the flashback took place when Bart was 7 and Lisa was 5.