When 12-year-old Homer starts to pick up Smithers senior's corpse, his glasses are on, but when it is full view of the corpse, the glasses are gone.
In the last scene, Homer and Marge are sitting on the couch, with a box on the table in front of them. Moe enters and sits down, the box is gone, and in the next shot, the table is gone.
In the scenes that Homer is 12 years old, Waylon Smithers (the one we know and love, not the father) is a baby. But this makes no sense - Homer and Smithers went to high school together.