When Dewey and Reese confront Hal in the garage while he is throwing paint onto the canvas, the paint color he is using changes from green to orange between shots without sufficient time for him to switch paint buckets.
While Hal is explaining to Reese what to do with the girl at his school, he first has food on his fork, then he has no food, and then again, has food on his fork.
When Hal shows his painting to his family, he uses a large-handled 2 inch(?) wide brush heavily laden with paint. When he kneels down the brush has shrunk to a one inch brush with little paint on it.
When Hal shows his painting to his family he has paint on the back of his fingers (right hand). Francis walks into the room, Hal falls to his knees and his knuckles are clean.
At the dinner table, after the boys leave the room, Hal's napkin on his shirt disappears.
Craig says he thinks he mistakenly mailed the inventory numbers to his mother, but in the season 6, Craig's father claims his mother died while giving birth to him, to cover up the fact that she actually had run off with another man when Craig was a baby. Up until that time, Craig still thought she was dead.