Without ever explicitly mentioning the 9/11 terrorist attacks, the debate surrounding the giant American flag -- as well as the board meeting in which people try to outdo each other in patriotism -- satirizes the overly patriotic mood that prevailed in the US during the months following September 11, 2001.
Per the title, "mother load" is a play on the expression "mother lode," which is a principal vein of gold or silver ore.
This episode offers the first close-up shot of the inside of Frasier's refrigerator. It contains mostly bottles and jars. Among the items readily identifiable are: a four-pack of ginger tea in bottles, a large squeeze bottle of ketchup, a squeeze bottle of French's mustard, a bottle of Arizona green tea, a carton of milk, a jar of almond butter, and a large salami.