When fleeing the Sheriff, the Simpsons jump over a railroad crossing onto what is clearly pavement. However, when the second train hits the car, the ground under the train is another set of railroad tracks that were not there before.
Ned reminds Homer that he was at Maude's funeral and that he fell in the grave. However, no such event was depicted at Maude's funeral in Alone Again, Natura-Diddly (2000).
When the Simpsons arrive in Palm Corners, Marge is driving in the middle of the road. Even if this is a one-way road, the road is wide enough to accommodate two cars driving. There's even a line the car is straddling.