When Andy knocks on Don's door to deliver the whiskey, two books are shown next to each other on his bed (James Michener's "Hawaii" and Michael Crichton's "The Andromeda Strain.") As Andy exits, the books have exchanged places and there is now a towel or blanket next to them.
When the tow truck drops off Don at his motel, it misspells the abbreviation for Oklahoma as "Oakla".
When Don pushes the young male hotel worker on the bed, there is one quick shot that includes the paper bag that held a bottle under his hand. It is missing in every other shot while Don reprimands and advises him; the reason is it fell onto the floor next to the bed, in a spot hidden from the camera.