So......hear me out, but I'm PREEEEETTY sure that the bits of rock work next to the Grinchmas tree and right behind the Grinch's red "dump shoot" transportation thingy is pieces from the now extinct Curse of the Mummy's Tomb! Looks EXACTLY like it! The construction, the look of it, the quality of it, etc. Maybe they saved a piece of it afterall!
The rock work wasn't even actual rock work, it was more like sculpted very thin rock work over some sort of sheet. Very primitive.