Given the incredible scope of The Legend of Zelda: Breath of the Wild and the many ways in which the game engine can pushed in different directions, it should come as little surprise to learn that it's possible to totally break the game if you so wish.
One Japanese player has discovered that if you use the flying mine cart trick during the "Bird-Man Research" mini-game challenge and you enter the battle with Calamity Ganon, the game goes a bit mad. You're returned to the Tower from which the Bird-Man Research quest commences, but the game world is devoid of NPCs and it's not possible to re-enter the battle with Ganon at Hyrule Castle.
Have you found any other ways to totally break the game? Let us know by posting a comment.