Stargate, as a franchise, has ten seasons from SG-1, five seasons from Atlantis, two seasons from Universe, a season of Infinity and a season of Origins. That's a LOT of ideas to work through and to be fair, that's a lot of plot lines that will eventually need to be resolved.
So, did Stargate manage to tie up all of the loose ends before it went off the air? The answer is both yes and no. While there are plenty of stand alone stories that never really needed to be tied up in a bow, there are other mysteries that really cried out for resolution.
Whether its the nature the four races in the alliance, or the lasting impact of the Replicator attacks throughout the Milky Way galaxy, there are plenty of questions that will still have all these years later. Follow on for this list to see if your biggest questions are still out there, begging for an answer that may not ever come!
10. Are The Reetou Still Out There?
The Reetou are a mostly peaceful race who have been hunted almost to the point of extinction by the Goa'uld. There are rebel factions of them who try to fight back against them, not by attack them head on, but by destroying all potential hosts for the Goa'uld instead.
This an ultimately self-defeating idea, though it doesn't stop a group of them from infiltrating the SGC and attempting to destroy Earth. With the help of the Tok'ra, they are stopped, though this leaves Charlie (the human child raised by a Reetou, who came to warn the SGC about the incursion) in the position where he is dying.
He is sent off to the Tok'ra so that they can put a symbiont in him to help save him. And that's it, the end of the story and the end of the Reetou plotline.
This idea of secret infiltration was an excellent story to introduce and is unresolved, even with Goa'uld still out there in the galaxy. There also needs to be a resolution to Charlie's story - did he survive, or did the blending process fail?