In Season 1, Judith's parents are called Sheldon and Lenore. However, in the seventh season, Lenore refers to Judith's father as Fred.
When Charlie and Lisa are talking in the coffee shop, a piece of white lint is on the backside of Lisa's clothing.
In the next shot it is gone.
When Jake refers to his father, Alan, as a 'doctor', Evelyn corrects him: "No, sweetheart, your father's a chiropractor. That's a masseuse without the hot oil." Since she was referring to Alan, she should have used the masculine form, "masseur".