Right at the end, in fact the very last frame, you can see a face in the snow as the shot fades out.

After the seance, Michelle Pfeiffer goes to drain the bathtub after it has mysteriously filled itself. Look closely, you can see the ghost moving in the mirror and again in the far right hand side of the bathtub even though Michelle does not see or acknowledge it.

Robert Zemeckis filmed most of this movie during a halt in the filming of "Cast Away."

There are more than a few Hitchcock references in this movie. Most notably Harrison Ford's character - Norman (Psycho), suspecting the neighbour of murdering his wife (Rear Window), Michelle Pfeiffer falling in the shower and pulling the shower curtain down with her (Psycho).  There are many others if you watch for them.

When Claire goes to Madison's house, there is a framed picture of Madison and underneath it, there is a newspaper clipping from "The Guardian" that is very prominant. This certainly signifies what Madison was to Claire.