Once you defeat all three planets (jungle, fire, ice) and have all three knights with you, travel to the Giant Asteroid in the Asteroid Belt (X-11 Y-84) and use the Golden Key to open the portal to Mordred's hideout.
(see related question)
you push through
buba dizzle
Mordreds secret hideout is between the two hay stacks, but first you have to get a key to go through.
there are haystacks push them then get the key
You go into Mordreds lab and grab a paper and turn it into her.
The small key in Astro Knights Island is for Mordred's secret hideout. When you come to that wind mill area, move the hay bales apart and use the key on that.
You have to power it up with manure which you have to get from the farmer near the secret hatch to Mordred's Hideout
find the coordinates to the moon under mordreds bedA pop. winner
You do not get or use a bucket on Astro Knights Island.
There is no treasure chest on Astro Knights Island.
In the fountain. you have to find the password first.
mordred's missing journal is in his study. his missing page is under his bed.