Hell, the color-correction on the nacelle Bussard collectors isn't even a change
it's just something that came through with the better quality of film! Do they really think that the original producers has blue BC's on the 2-foot model but red ones on the 6-foot? No, there's many shots of the 2-foot model where the colors are all weird usually with the Bussard collectors/warp field grids taking on the color of something else in the shot. Just an oddity of using videotape, the film makes the "real colors" come through.