Once again, a scholar goes haring off in search of a mysterious artifact without taking proper precautions. And note the listing of the ring's owners. No surprises, there. If they were famous conquerers, they must have owned the ring.
Anyone notice that part of the devil-worshippers' chant is 'Om Mani Padme Hum'? A case of 'As long as it sounds foreign,' and an insult to audience intelligence. That's a meditation chant from India.
Really, who was surprised by that last scene? You could pretty much predict it would happen. It's no longer a twist. I don't think it was a twist at the time.
When you make a horror movie, your music shouldn't sound like it was originally intended for an action film with lots of horse-riding.
Hm. Should check the date on the movie. That Pazuzu reference sounds like someone saw 'The Exorcist'. Pazuzu was from Mesopotamia, so the amulet can't be Egyptian.
The usual mishmash of pop-culture fakelore, rather than authentic folklore or scholarship.