Bart's tape binding changes positions between shots.
Walt says his radio dial never strays from 89.4 The Spur. However, Springfield is a US city, and no FM station has an even number after the decimal.
Incorrectly regarded as goofs: The showdown with Bob takes place at "Five Corners", a reference to the real-life "Four Corners" of the U.S. where New Mexico, Arizona, Utah, and Colorado meet at a specific spot. Obviously the "Five Corners" here aren't based on that, otherwise Bob wouldn't be arrested by cops who are clearly from New Jersey. But this bit is having fun with the fact that the show takes place in a permanently undefined part of America, so if Springfield somehow does border odd states at any point, it's not an error at all.
In this episode Bob is seen sharing a prison cell with Walt Warren, despite previously showing that he was in a cell with his entire family in "Funeral For A Fiend".
Bob tells Bart that the term epitaph refers to your last words when in actuality it refers to the writing on your gravestone.