The third film in a trilogy often tends to suffer. Jaws 3, Spider Man 3, X-Men: The Last Stand… the list goes on.
The Mummy 3: Tomb of the Dragon Empire suffers from the rule of three syndrome to no end. Picking up some 15 years after the events of The Mummy Returns, we find Rick and Evey as retired civil servants, fresh from the Second World War, and bored out of their minds. This wouldn’t be too much of a problem, being a believable scenario for people with their past misadventures; had it not been for the single biggest, most catastrophic mistake the producers could have made. Evey!