Hober Mallow wrote:
So changes had to be made. Emily's age was retconned and made into an important plot point. The year was retconned from 1996 to 1999.
I don't see that as a retcon of the universe as a whole, just as the passage of time. I assume that the series cliffhanger was rendered apocryphal and that in the revised continuity, three years passed before the Purist attack on the Franciscos.
Among Alien Nation fans, I don't remember any issue at all. No one talked about continuity, canon, alternate universes, or anything like that.
Personally, I never liked the finale episode. I felt it was too contrived, forcing all the characters into somewhat gratuitous crises at the same time. I suppose that's become fairly standard since, but it felt very forced and arbitrary to me at the time. So I was happy that the movie essentially erased the episode from continuity.
I hadn't noticed the other continuity glitches you mentioned between the series and the movies, but there's a huge one in the last movie, The Udara Legacy
. That movie treats Newcomers in their 70s as being senior citizens, even though the series had established that Newcomers live considerably longer than humans and George already was in his 70s, or at least late 60s, and yet was equivalent to a human in his 30s.