Space Quest 1
If you are traveling in the escape pod, and press the "don't touch" button, you'll see a funny little egg involving Ken and Roberta Williams living in Castle Daventry.

If you talk to the Sarian guard he will ask if you played KQ2. If you respond yes, you receive points.


Space Quest 4
In Space Quest 10, after youve killed the guy in the nest, Graham will fly by, being carried by the Roc in KQ5. You must slow it REALLY down to see it.

In the software store Hrz so good, there is a game box named King's Quest 48:The quest for more Disk Space

If you play the Mrs Astro Chicken game, Cedric will occasionally fly by on the video screen (You get 50 points if you hit him).


Space Quest 6
In the Airport when you give the big guy the donut, while hes transforming, he becomes for a couple of seconds a big woman singing "Girl in the Tower"

In Roger's bedroom, look in the mirror.