The Paramount explanation was that to fit it all on one disc they'd have had to use a special process that would have taken longer to produce. Supposedly there are only 2 production houses in the world that do that technique, and Paramount wanted the release date to be the same or close to that of North America, so they went with two discs.

While it seems like it should be able to fit, don't forget there's the dolby 5.1 audio and the commentary track that take up extra space, too.

At first I was annoyed that it was on two discs, but it didn't bother me when I had to actually swap discs. Recall that we always had to swap tapes before, for all three films, and even more for laser discs, so I think we've gotten a bonus with GF1 and GF3 on one disc.

JG