If you didn't see the snake reflection than it couldn't have been an original print from the '80s. (I'm pretty certain that it was first taken out for the 1999 "Complete Adventures" VHS releases but my memory about this is getting foggy.
Definitely no earlier than that, though.)
Did the Cairo street scenes have an overbearing
yellow hue to them? That is one of the most glaring visual differences of the new, revamped version.
From what I've gathered, it seems that major chain theatres which have been showing the trilogy, since 2011, are screening the "Blu-ray" prints with only the smaller movie houses & repertory cinemas showing the originals.
Anyway, Andy, I know what you mean about the surround sound!
When I saw the IMAX version last year, I was hearing all kinds of things that I'd either forgotten about over the past 30 years or were brand new additions (and there were definitely some new sounds). So cool to discover more nuances about such a beloved film, ain't it?
I haven't seen "Doom" in the theatres since '84 but can remember hearing the slave children screaming from the rear corners of the theatre right after Indy steals the stones from the altar. The 1st time I saw it (on opening day), I actually thought that they were coming from kids in the back seats! They were creepy and helped make the film an immersive experience. So keep your ears open for those screams next week!