Disk 3 of the game contains a map & graphics which are not used in the game. These graphics are accessible by modifying the disk.
This is the map:

You can walk around this map but the exits lead to nowhere. When you try to engage the metal creatures, Gilian only screams Whaa help!, without having to fight the them.
As you can see, there are some clones (?) of Gilian in this map. When you talk to them they ask Gilian who he is, that they are no Snatchers and that they are a real extra (sic). Well, this is what they say in the English translation, I don't know if this is identical to the original Japanese verion.
Now, where were these graphics supposed to fit in the game? Frankly, I don't know, but since it is on disk 3, it might be a part of Syd Garden or the Snatcher base.