I agree, the anthology fits more with short films.
There are lots of stories of missing people. Undoubtedly there are rational explanations for these disappearances, but these stories can serve as inspiration for the fiction of a film:
Franklin's lost expedition
Franklin's lost expedition was a failed trip of the British exploration in the Arctic, led by Captain Sir John Franklin, who left England in 1845.
http://en.wikipedia.org/wiki/Franklin%27s_lost_expeditionThis tragedy inspired a horror novel.
http://en.wikipedia.org/wiki/The_Terror_%28novel%29
Percy Fawcett
This adventurer disappeared while looking for an ancient lost city in the jungles of Brazil.
http://en.wikipedia.org/wiki/Percy_FawcettLost Colony of RoanokeA colony that disappeared during the Anglo-Spanish War.
http://en.wikipedia.org/wiki/Roanoke_ColonyMary Celeste
It is considered a ghost ship, because it was found in the Atlantic Ocean, full sail without crew, bound for Gibraltar.
http://en.wikipedia.org/wiki/Mary_Celeste
Dyatlov Pass incidentThe Dyatlov Pass Incident refers to an event that occurred on February 2, 1959 in the Ural mountains, in which nine young skiers were killed in mysterious ways.
http://en.wikipedia.org/wiki/Dyatlov_Pass_incidentIn addition, there are a lot of mythological creatures. Then on the premise of a movie, the presence of Predators on Earth could have served as inspiration for these myths and legends. For example Spring-Heeled Jack