There's something quite amusing with the development screenshots of C3A2. The maps are mostly untouched between retail and the maps from around mid-1998. Some minor changes like a hallway being closed up and the portal sprites just being colored rectangular prisms. (First and third photos are pre-release and second and fourth photo are retail.)
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There's this earlier 1998 screenshot that shows the map before it got the finalized textures.
This version also depicts that the silo was taller than the final game. Would the textured version contain this difference? Who knows!