Watch Titanic's Achilles Heel Full Movie Free Online 123Movies. An expedition looks into whether Titanic's hull had a construction design flaw that caused her to break apart. Featuring advanced CGI technology, archive documents and photographs, as well as footage from the modern-day History(R) expeditions, "Titanic's Achilles Heel" is a remarkable journey into the ongoing legacy of a ship that continues to capture the world's attention.