One thing that I thought that I haven't seen mentioned here is that the Alien seen in the final shot is actually the Queen alien. It was created by the *SUPER* facehugger, and the last thing we see is it's lower jaw extending from it's bridge, in the same manner that the Queen alien reveals itself. It also would explain where all the eggs come from, where there were none in this movie. So that would leave 2 items that conflict with the original Alien, the Space Jockey not being in the chair, and the name of the planet. Both of these could easily be explained with some creative writing, the Queen or something else could have carried him there, and the planet naming conventions could change in the time between this movie and the original.