During the Foot Race event a villager will be standing nearby using a gun to signal the start of the race.
This stands out as unusual not only for what the item is but also because it's one of the few items that only NPC's can use.
While this is believed to actually be a cap/cork gun,
with the simplistic graphics of the time it can easily be mistaken for a realistic pistol.
Regardless of what it actually is,
it’s funny to think that of all the first party GameCube games Animal Crossing is the one to feature a realistic looking gun.