It just seems like a glitched field to me. There must be tons of them in .hack.
Well, there are a couple glitched fields indeed, but they've been found out of luck pretty much, simply inputting a random set of keywords wanting to train or get items, and then finding out there's something wrong with the field XD Here's my list of glitched areas:
Delta: Upfront Starting Berserker
-Third floor "haunted", no monsters and "invisible" PKs appear. (Rebirth only)
Delta: Fattening Ruined Fast Horse
-Waterfall glitch. The waterfall background of the Beast Statue's room overlaps in the room right infront of it. The effect can be seen on both sides.
Delta: Graceful Wrath's Shadow
Theta: Concealed Friend's Moonlight
Theta: Roaring Friend's Moonlight
Delta: Spring's Black Hand Song
-Plataform glitch with Return Feather/Plataform Transport on a nearby hill, allowing you to go underground (Rebirth and Reminisce only)
Theta: Galloping Wrath's Blue Cloud
Theta: Galloping Military Blue Cloud
Theta: Galloping Engaging Blue Cloud
Theta: Galloping Swift Blue Cloud
-There's a gap in the map that allows you to travel off-limits.
Theta: Starting Wrath's Blue Cloud
Theta: Starting Military Blue Cloud
Theta: Starting Engaging Blue Cloud
Theta: Starting Swift Blue Cloud
-There's a gap just like the above, letting you walk through water, and letting you go underground if you walk enough to get off the water's limits.
As you can see in the last 8 fields, they have very similar names because they're all equivalent/mirror fields....dunno how the map generator for GU works exactly, but there are areas that share the same map and characteristics overall (there's also another dungeon like Upfront Starting Bersker, with nothing in the 3rd floor in Rebirth, but i forgot it XD It's the area you get by changing "Starting" with the keyword below, that should give you a parallel field but of a different type, be it Cave or Shrine). So, if you find a glitched area, there's a high chance that the glitch will be reproduced in it's respective mirror area. The only exception i've seen is with the Waterfall glitch, just because the Beast Statue's room in Shrine areas don't have a huge graphic like the waterfall. That said, there's a high chance that this area also has a mirror area with the very same glitch....but, given how it seems like the mirror area is the actual Quest area, and this area itself could've been modified out of the generator (like some Quest areas and all Lost Grounds are), there's also a chance it's unique.