As I remember the ending, everyone except Jack had entered the gate in order to return to the SGC. Jack was talking to one of the good/bad guys and so had not entered the gate. The wrong thing about that (which the writer apparently didn't think of) was that after being on that planet for a month or more with no contact with the SGC, their security codes would have been locked out and by entering the gate without putting any codes in they pretty much splattered up on the iris on the SGC end. From what I recall, they were supposed to have gotten back to the SGC to find that it was run by Germans/Nazis or some similar society and it wasn't exactly their earth. I assume we were supposed to find this out in the 2d book that wasn't written.