How to Train Your Dragon 3 Coming out March 1, 2019. So we rewatched the old movies. A question that popped up was, “How did Hiccup lose his leg at the end of the first HTTYD movie?”
The ordeal happens when Hiccup and Toothless are fighting the Red Death which is the villainous colossal Dragon near the end of the FIRST movie.
All seems well Until Hiccup and Toothless are unable to avoid the red death’s tail.
When Hiccup and Toothless are Knocked Away by the Large Club on the end of the Red Death’s tail, Hiccup is knocked unconscious and starts to fall back into the fire.

Fanart: https://demonml.deviantart.com/art/Ni...
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Toothless saves Hiccup in How to Train Your Dragon:    • Video