Easter Eggs in King's Quest I: Quest for the Crown (SCI)
Egg id: 417
At the gate which leads to the land in the clouds, try to "pick lock" for a reference to the "Famous Adventurer's Correspondence School", which is a reference to Quest for Glory 1 and 2.
In the preservation lab, Vat 14 contains King Edward of King's Quest (see also the listing of the vat contents on the desk of Ernie Leech). Vat 10 contains the unicorn from King's Quest 4. Vat 9 contains lemmings.