In a medium bowl, combine the mayonnaise, garlic, onion, and seasoning.
Rinse the duck and dry it with a paper towel. Rub the duck with the mayo mixture and cover it tightly with plastic wrap. Allow it to marinate in the fridge overnight.
The next day, wipe off the excess marinade from the duck. Clean and chop the carrots into large chunks and slice the apple into about eight slices. Stuff the duck with rice and place the carrots and apple slices on top (this will make it easier for you to remove them after baking).
Bake the duck at 300°F for about 90 minutes, or until it turns golden brown on the outside.
Before slicing, remove as much of the carrots and apples as possible. Slice, serve, and enjoy!