Specific holidays, such as Christmas and Halloween, have been either eliminated or replaced, with Christmas in particular being replaced by the very similar "Toy Day." The game has its own special holidays and events, though, so the loss of these is felt less since there are still events to celebrate.
The player begins the game in a taxi cab in which the driver, Kapp'n, asks a series of questions that determine the appearance of the character, as well as making sure that the internal clock on the Nintendo DS is the correct time.
You need to enter then exit a house to see the changes, which can't be reversed once saved.
While used by many people just to customize their own town layout, some used them during Wi-Fi visits in other players' towns to create game-breaking layouts that may trap players irreversibly..worse, cause the game to crash by overloading the system and rendering the game useless if it crashes on the title screen (as the Erase File option can't be accessed). (later used in Animal Crossing: New Leaf) Come in sets of 2, 4, and 5.
To access the crash dump screen, first crash the game.