UnnamedCharacter has extracted some fantastic images from the core files that make up Wing Commander 3! He has been experimenting with the programs in his WC Toolbox package to dig deep into the game. While exploring some of the background scenes used during game flow, he has come across a variety of alternate settings that appear to be preliminary prerelease versions of most locations.
The barracks are smaller with beds lining the walls. The bridge has significantly more glow from the various screens and safety lighting around the edges. Its framing has also been pulled back farther to reveal the central captain's chair as well as steps to the upper level. Flight Control pulls in closer to Rachel's terminal, and the loadout screen has been replaced with a video feed of the hangar. TrainSims are also not yet present. We see the flight deck from a more central viewpoint that looks out the bay doors. Gunnery Control is relatively unchanged, but the computer consoles were updated. Even the elevator got some tweaks in perspective and how the interface UI is presented. As previously mentioned, the bar (and barracks) furniture is an overlay, but the lighting seems to have been microscopically altered at some point as well. It's amazing what discoveries continue to be made after more than 25 years!
No updates to the toolbox, but I have been digging through the WC3 dataset and found what looks like early room designs. I do not recall ever seeing these before.