This case hinges on a hypnotic retreival of 'buried' memories, a technique which has very little credibility nowadays.
As I mentioned on
this thread, I experienced a slight case of sleep paralysis myself, and saw an alien very similar to the one described by the Hills. I am sure that such images are very much influenced by popular culture, particularly films and TV; in that thread I gave examples of comparable alien images stretching back to H G Wells. Betty Hill is said to have been a fan of such films, including
Invaders from Mars mentioned in the link.
Not it turns out that an episode of the Outer Limits was shown on TV in the states a few days after the so-called Hill 'abduction', but
before the hypnotic regression took place; on that episode there was an alien which resembled the one decribed by the Hills -
here it is; I think we can probably trace the Hill's alien experience, and the predominance of the Grey alien image in UFO culture, to that particular image on an early 60's TV show.
I also have grave doubts about the so-called sketch map of Zeta Reticuli; the perspective seems way off. When I have time, I'll check it against the locations of those stars as determined by Hipparchos (using Celesta) and report back.