After you copy the star data from DVD, you'll need to run a Python
script at http://ad.usno.navy.mil/ucac/modifs.py
to correct a few thousand erroneous proper motions. See
http://ad.usno.navy.mil/ucac/readme_fixHPM for details.

I also know that Vega is missing from UCAC4. It might not be the only one.

-- Bill Owen