In a stylized title, you might be able to leave out the first "the", i.e, Weight of the Soul, but the second one I think is absolutely necessary. Soul, without "the", would sound like you're talking about soul music, or that elusive quality known as "soul", which is quite different from "a soul" or "the soul".

I agree translating "es heisst in einem Film" is tricky. Keeping the impersonal construction leads to some awkward English sentences, but I understand why you might feel it necessary.