Anyway, a lot of it feels like the early 1e modules that had a loose tie to Greyhawk. They had more or less official locations in the setting, but DMs were free to use them however they wanted. The Tomb of Horrors for example, is given 6 different suggested locations in Greyhawk, but there's little else tying into the setting. A few years later, The Temple of Elemental Evil is much more tightly integrated into the setting (to be fair, I've never compared it to T1 to see what kind of differences there are between the two though). D1-3 are the only other early 1e adventures I've looked at, and while they too are Greyhawk, I wasn't particularly interested in the setting ties myself, as I was researching material on the Underdark. So I don't remember exactly what Gary did to tie that in with Greyhawk, I was much more interested in his descriptions of the drow, kuo-toa, and Underdark in general.