Why didn't Alternate Mitchell disappear? (spoiler)

[Amon Ra]

When you change the timeline, people disappear and are replaced by their new selves. This is what happens at the beginning of the movie. Vala, Teal'c, etc. disappear, while Mitchell, Sam and Daniel don't because they in the stargate's temporal vortex when their turn came.

But then why didn't Alternate Mitchell disappear after he killed Ba'al on the Achilles? Shouldn't he have disappeared since a new Mitchell went on to be born and the Tok'ra extraction ceremony went on normally?

[Snowman37]

The rule for Stargate has always been that the time travelers who change the past are left uneffected. When Ba'al and his Jaffa go back in time to change history, none of them poof out of existance given they would exist differently in the new timeline. We can presume that Ba'al would have killed his alternate timeline self and taken his place. When Mitchell goes back in time (at the end) to kill Ba'al, he would have lived out the rest of his natural life in the shadows so as to not disturb history. However, I'd like to have seen a final scene to the movie where General Landry begins debriefing SG-1 on what their other selves did based on letters an elderly Mitchell who wouldn't have lived long enough to see 2008.

At the beginning of the movie, everyone is vanishing because the timeline is "resetting" thanks to Ba'al's presence in the past. Mitchell, Carter, and Daniel escape the timeline reset thanks to their unkowingly well-timed Stargate trip.

[KEK]

When you change the timeline, people disappear and are replaced by their new selves. This is what happens at the beginning of the movie. Vala, Teal'c, etc. disappear, while Mitchell, Sam and Daniel don't because they in the stargate's temporal vortex when their turn came.

But then why didn't Alternate Mitchell disappear after he killed Ba'al on the Achilles? Shouldn't he have disappeared since a new Mitchell went on to be born and the Tok'ra extraction ceremony went on normally?

The past changes the future, the future doesn't change the past. Another Mitchell being born in the future couldn't magically make the one in the past disappear.

[Gurluas]

I believe the reason he did not disappear is that he was not supposed to exist in that timeline so he is not attached to it.

And of course the whole timetraveller thing.

[ArchaeoNerd]

Mitchell had to hang around after killing Ba'al, otherwise how would he appear with his grandfather in the picture on the locker? I think that in the Stargate universe when someone "fixes" the timeline, it's not really restoring it back to the original timeline exactly the way it was before, but creating a new timeline that will be almost exactly like the original (i.e. after "Moebius", now there are fish in Jack's pond). So Michell created a new timeline that was almost exactly like the original one should have been except that in this timeline, he knows his grandfather. This Mitchell won't know anything about what the original Mitchell did back in 1939, but obviously history changed so that the Mitchell we see at the end of the movie was acquainted with his grandfather.

ArchaeoNerd

[SaberBlade]

There were always fish in Jacks pond, he's just a crap fisherman. If I remember right, that is what one of the PTBs stated. So things do go back to normal.

Moebius is a good example though, because Jack, Sam, Teal'c and Daniel were still in the ancient Egypt when the timeline was changed in part 1. When the part 2 versions went back, they met original Daniel.

Kek said it best, "The past changes the future, the future doesn't change the past" so when you go back and change the future, it doesn't affect you personally, but it can affect the future version of you now created by the changes.

[Snowman37]

There were always fish in Jacks pond, he's just a crap fisherman. If I remember right, that is what one of the PTBs stated. So things do go back to normal.

Watch the end of "Threads," then the end of "Moebius, Part 2." In "Threads," there is no fish. The scene isn't extended, the fish is added before the camera pans out as it did in "Threads." The timeline DID change. However, it was for a laugh. The writer didn't expect everyone to analyse it to death.

[Dr. D.]

Disappearing Cams, it makes me think of Back to the Future, yet it would be a bit backwards for a previous version of the character from the present who is living in the past to disappear in favor of the next version of the character from the present who is living in the present.

Brad Wright pointed out in an interview about Continuum, "that time line ceases to exist." In the same interview he said of Cam, "he can't change his own time line."

A lot of people questioned what Mitchell did between 1929-1939 or after that. He probably just lived his life and focused on minimizing collateral damage, trying to help the time line return as close as possible to the version with which he is familiar.

Another interesting perspective that I've seen other viewers bring up is the notion of Cam's grandfather not being his grandfather at all but another-another version of Cam from a previous jump to the past but that he jumped a little bit too far back and ultimately ended up failing the mission. The different nose can be explained as him simply have broken it. However, there's nothing that openly points to that being a viable option. Yet, then again, a lot remains unspoken during the scenes that his grandfather character is seen in the movie.