Arwing

The Arwing is the title of the spacecraft flown by Fox McCloud in the Nintendo StarFox series. The ship has many different models such as the Arwing II and various other forms including a land tank. The Arwings relevance comes to Zelda as a hidden enemy, which can be unlocked via an action replay. Once found, the Arwing attacks similar to other flying enemies, however, the Arwing doesn't fire its laser weapons from the StarFox games.

The reasons for the Arwing being in the game, under the surface, is unknown. Its likely the designers placed it in the game as an April Fool's style joke as a surprise from Nintendo executives playing the game or quality checks. Its also not known why the Arwing wasn’t removed before release, and it certainly possible to find within the games code in cartage form if not as well as its GameCube and Virtual Console counterparts.

P.S. Arwings are cool. :)