The license plates on Mr. Anderson's truck read D3W-08U, but when he's ripping the tree out of the ground, it changes to ABC-1234.
When Beavis breaks the window with the hose, the glass falls outward. If a pane of glass breaks from being struck, the glass would fall the same direction that the force was applied, ie if it was struck from the outside of the house, the shards of the broken window should have fallen into the house, not out into the backyard.
It makes no sense for the duo not to sustain any more cuts while rolling around in the broken glass on the ground.