King's Quest I has several Easter eggs hidden in the game. All of these Easter eggs found courtesy of Erpy walkthrough.
Easter Eggs
Look at the smoke rising from the cauldron several times. On occasion, a face of a monster appears.
Note from witch's house
If you read the note from the witch's house several times, every once in a while it will read something else.
More to come
(More to come, I just don't feel like rewriting what Erpy has already written!).