Why was it called 'After.Life' instead of 'After Life'?

It is to distinguish the present film from the already many existing films that are entitled (or at least contain the words) "After Life" or "Afterlife".

because this movie is pretentious.

More ambiguity?

More ambiguity?

Probably to simultaneously connect and separate the two words. “Afterlife” being a theoretical place or state of being that exists after death, viz that Eliot actually did have the ability to interact with such a plane, and “after life” emphasizing the point at which one, while technically alive, has stopped “living.”