Acheron · 41-45, M
Because it's a movie and the writer thought it would make for fun cinema. The factual accounts the story was based on don't indicate they were buried alive.
Oldanglaisadverbs · 46-50
@Acheron Do you already know about this?
Acheron · 41-45, M
@Oldanglaisadverbs Yes. The info is out there. Just like any writer/director does with movies based off true stories there are liberties taken to bump the entertainment value.