"These are among some of the 'lost' features", curious, which are the others.
That's all I was able to find - "Against all the odds, Pegasus Prime will finally be available for the first time to play on the PC. The game's unlikely resurrection has brought in many benefits. The soundtrack is of better quality, using sources like the unreleased US PlayStation version for Andrews' and Stewart's original music. Many of the sound files sampled at 22KHz have been replaced with files sampled at 44KHz. The cut scenes from the DVD version have been re-rendered at their full original resolution in higher bitrates, eliminating the pixelization that plagued the CD-ROM version. Lastly, some previously cut or unfinished interactive sequences (including Easter eggs) have now been restored."
For the curious: The interactive sequences replaced are the Mars Canyon chase and the NORAD Sub chase sequences. They also added in a number of music tracks that were in the original Journeyman Project release but were removed for the initial version of Pegasus Prime.
As for the easter eggs, well, they're secret. ;-)