In the beginning of the movie, the General claims that the Stargate is about 10,000 to 15,000 years old. Most any astronomy book will tell you that even 5,000 years ago, that all the constellations were somewhat warped compared to todays versions. Other than that, it was a pretty cool movie.
The constellations were not really warped, but they were different than they are today. Since the Earth is on a tilted axis, the constellations would appear to have "shifted" to a slightly different spot than what they are today.
The other thing here is when they are at the new planet. The scientist said he would be able to figure out the signs (constellations) to get them back home. If they are millions of light years away from earth, how does he know what the constellations look like from the angle on the new planet if he never studied them at night. Or, where the earth would be in regards to them ........
P.S. Don't say the chartuse was a map for them. Why bother with so many symbols and only 2 destinations? Or why only 1 chartuse instead of 50 and they have to figure out which 1 to use ........
As I recall, in one of the early episodes Maj. Carter said that Abydos and Earth were relatively close, so it would take a much longer time for the coordinates to change.