Mobile Suit Gundam: Cucuruz Doan's Island

After a covert mission goes wrong, Mobile Suit pilot Amuro Ray and his comrades are stranded on a remote island. The battalion was sent to a land called the Island of No Return to clear off any enemy forces, only to find a group of children and an enemy mecha attack. Now Amuro must find a way for them all to escape this mysterious land, but not before meeting a strange man—Cucuruz Doan.

Note: Announced at the "Dai 2-kai Gundam Conference" event, the film is described as a retelling of the 15th episode of the original Mobile Suit Gundam television anime. The episode itself has been omitted from English releases of the series.
(Source: Crunchyroll, Anime News Network)