Mild spoilers below:
The film has
Ghosts/spirits haunting the living.
If Supernatural is any indication, I believe the film is on topic, but I wanted to be sure.
If it has supernatural elements, and they are real, or at least potentially real, then sure, it's on topic.
By "potentially real", I mean that those supernatual elements are treated as legitimate by the movie, and a casual viewer cannot tell that they are "obviously" faked, imagined, hallucinated, imagined, etc. For example, in the original-run Scooby Doo, cartoons all of the supernatural elements are clearly faked by the villain of the week, so that would be off-topic. (I think this might not be true anymore, either, but that's the best example I could come up with.)
As such, questions about the supernatural elements of the film are clearly and firmly on topic, whereas questions about other parts of the film would probably be best asked elsewhere, for example on Movies:SE.
The film was marketed as an "Exciting supernatural thriller", which would strongly indicate that the studio (at least) felt that the presence of ghosts was a given:
However the film's co-star feels that the supernatural bits were all in her mind
Q. So you don't think Michelle's character sees a ghost?
Harrison Ford: If you look at the film carefully, you will see that the ghost - the manifestation - can be seen as an effort by Michelle's sub-conscious mind to remind her of the events that she has repressed.
I'm saying no because there's no actual evidence of a ghost (we could be seeing hallucinations caused by the protagonist's trauma-induced psychosis).
Everything in the movie can be explained by trauma, repressed memories and hallucinations.
In my opinion What Lies Beneath fails the is it Sci-Fi guidelines