From the "Special Features" menu, hit left to highlight the snowglobe. Press enter to access an alternate "snowglobe" menu system.
Once in this alternate menu system, the original menus can be re-accessed by going to the "Scene Selections" menu. Once in, press up twice to highlight the dead fly. Press enter, and the old menus will return.
An alternate keepcase cover can be found by reversing the original cover art. This new cover contains a map of the various events that take place during the film.
Reviews: DVD Talk also has a review of
Fargo: Special Edition by James W. Powell.