In the beginning of the scene where Donna and Kitty are baking cookies, Donna puts a third cookie down on the cooling rack. The camera pans away to Jackie and Eric for several moments. As it returns to its previous viewpoint, there are only two cookies on the rack and Donna is putting a third cookie down for the second time.
Leo thinks he's won a million dollars from a dead uncle and he takes Hyde and Fez on a shopping spree where he (Leo) buys them (Hyde and Fez) many items. In the end, they all find out the letter that told Leo about the money was actually a contest entry letter (and the dead uncle was Ed McMahon) and that Leo never had the money. If he didn't have the money, how did he buy the stuff in first place?