The most recent thing I noticed was a goof. (I notice the mistakes of others, but remain oblivous to my own. Sue me.) Watch the big stone ram-horned head on the Gozer temple tumble–I partly disappears behind the matte painting of the temple cap, as does the dust and debris.
And an alternate take on Matthew's “Venkman, Stantz, Egon” note. Perhaps Pete's calling Egon the “diva” of the crew, the one for whom one name says it all. And I just thought of something–I don't think Peter calls him “Spengler” the entire movie…
One more thing: Louis' fly is down on the Gozer temple. Didn't mean anything to me when I was 11, but later the whole Keymaster/Gatekeeper thing had new meaning.