msycamore, I noticed when comparing to the ITA version that there was some cropping on the right hand of the frame. When the ITA pans to the right of frame, more picture info was there. I think some amount of cropping occurs in a lot of Laserdisc era letterbox transfers.
Any other picture oddities might stem from the fact THX was filmed in Techniscope, or even the print they used for the transfer to begin with.
I think the Beta was cropped on all sides, actually. The color on the titles is pretty close to what I saw. The AZ logo looks good too.
It's also possible that for the DC they have gone back and used a different source for the Buck Rogers footage.