The mouse is in the Maid's room of the castle (first floor left side). You can capture him with cheese you find in the dungeon.
The mouse is in the room (in the castle) where the maid is. Set it in the maid's room (where the mouse is) and the mouse will eat it. Then the mouse will appear in your backpack. To release it, press the mouse card.
It is a mechanical mouse. (see related question)
Click on his card in your items bag.
The mouse will get surprised, run around, then run back to you.
You do not get or use a bucket on Astro Knights Island.
There is no treasure chest on Astro Knights Island.
Feed it the mechanical mouse (from the Maid's room) and the owl will follow you.
After you get the cheese you put it in the princesses dressing room and capture the mouse to feed it to the owl.
There are no bird eggs in astro knights island.
To catch the mechanical mouse, in the Princess's Maid's room (castle first floor left).
its on the island
At Mordred's secret lab, when the owl flies out, you feed the mouse to the mechanical owl. The owl becomes your friend and follows you.
How do you talk to the girl in the hay loft at astro knights island?