It is well established that the trip back in time is 'one way.' Skynet would have no means by which to pull their terminator into the future, after doing the deed. One could argue that there would be no need, as the war would have been prevented, in favor of the machines winning, therefore there would be no need for them to bring it back up to present time.

But that argument omits all the other (more egregious) issues with 'Carl' the T-800. To name but a few of the many:

Skynet only sends units back in 'read only mode' to prevent them from deviating from their mission in any way. The only way to change this on a T-800 model is to remove their chip and tamper with it, as established by Terminator 2. Carl, having been programmed to kill John, would not then be able to rely on any human to open up his cranium and change him from 'read only' to 'write data' in order for him to learn to adjust to society. The franchise has never established what an 'evil' terminator would do after successfully completing it's mission, as they've never been successful (lol fail). If they cannot self-terminate, they would likely have certain routines in places to assist with the rise of Skynet, lists of secondary or tertiary targets for elimination, or just go into sleep mode at a designated safe location until the war begins and Skynet reactivates them for the war effort, as necessary.

As well, the idea that he would 'search for purpose' is not a machine-like thought pattern, and smacks of poor writing for plot convenience. The idea that a cyborg with precisely written programming would simply 'lose purpose' and turn coat and start giving its nemesis, Sarah Connor, the coordinates of his own Skynet allies, is absurd, due to the 'read only mode' that I mentioned above. He would have no programmed purpose to have any concern or purpose for helping Sarah in any way (as he explains in the film that he was helping her so that she would have purpose).

Furthermore, how did 'Carl' even know the locations of the other terminators? Theoretically, Skynet would send back many, many units for various purposes, and some or all of these would be aware of each other, as well as aware of units which Skynet planned to continue sending back (i.e. "Carl, we will send back a T-1000 to such-and-such a location at such-and-such a time, with this mission. Assist this unit, once your mission is complete. Request assistance from this unit with 'X' priority if you are unable to complete your assignment.") But the problem with this, is that he was successful in performing an action which was specifically designed to change the entire future of the conflict, meaning that those other units would very likely not be sent back to the same place or time for the same mission(s). So Carl would have no way of knowing this stuff, and the film doesn't bother to even attempt to explain it.

Those are just a couple issues with Carl. The movie as a whole has many, many, many more issues that are worse than these.

I take your point that it's a one way trip - I forgot about that, but as this is a Legion Terminator then it doesn't have to be a one way trip. Skynet is null and void in Dark Fate. I believe you keep referencing Skynet in your above post when it should be Legion.

Another geeky observation - a Terminator robot must have some sort of power cell to maintain full operational status. The robot can't run indefinitely. Without some charge it would shut down. Perhaps Carl plugs himself into a phone charger.

That's fair to make the distinction between Legion and Skynet. Carl was sent by Skynet, therefore any and all conceived issues regarding Skynet continuity and canon are still valid. Insofar as Legion is concerned, I think it is plain to see that the script is attempting to run a soft reboot of the franchise, hoping to pivot away from "John Connor vs. Skynet" by killing John and changing Skynet to Legion. As such, they got lazy by not explaining or introducing enough background data to understand what the limitations of their characters are, given the knew dichotomy of forces.

Legion is little more than a placeholder for Skynet, with the writers looking for a new name for the same enemy. Skynet originally had just enough time/energy/wherewithal to send one unit back before being defeated by Mankind. They elected to target Sarah, because there was insufficient data available to target John at a suitably vulnerable period. As per that continuity, T2 never should have been made. As soon as the ability is granted to send back multiple units, there is then no reason for Skynet to do anything less than flood the past with dozens or hundreds of HK units to effectively wage the war in the past, instead of in the future. But T2 gets a pass on all that, because it's such a well-made film and it's so bloody entertaining.

And to your point about the limited lifespan of a terminator - it's approx. 120 years for a standard T-800. One may safely assume that later models would have more efficient power cells, thereby lasting longer. Furthermore, the one in T3 had a back-up power cell, meaning it could probably last even longer. Beyond even that, who knows how long they could last in a "hibernate" or "sleep" mode. Skynet could effectively send a unit back to 1950 and have it wait for Sarah to be born, and go after her as an infant, or even go after her mother, and still have it around and viable to fight the war in 2029. The possibilities spiral out of control, because time-travel isn't a phenomenon that humans can successfully make sense of, because it can't actually happen. They originally went for Sarah when she was young, because they couldn't pin down John's history (which makes little sense, as he was in the foster child system, meaning the government would have record of his placement, parents, etc.) and so they had to go for her. T2 sort of glossed over that wrinkle, and just had the T-1000 go for John as a kid, without explaining how Skynet knew where or when to send the thing.

The overarching issue here is essentially this: The original story did not leave any room for a sequel, and yet sequels were made. In some fact or other, the sequel is going to have to retcon the original story, or just ignore it (as in T2). So, you are correct that Legion could simply be written to have more capability than Skynet, but that immediately sends the whole of the story into a downward spiral of nonsensical time-travel bullshit with terminators not being utilized effectively. I mean, why not just send the terminators back to 1900, have them develop Skynet themselves, have them develop nukes, and have them wipe out humanity when the weaponry doesn't yet exist to effectively combat them? You see the problem?

Honestly, when it comes to questions of, "why didn't they use time travel like this, instead of like that?" then you're never going to get a satisfactory answer, because time travel precludes that possibility.

@fan_of_films said:

However... if Skynet or whoever is in charge in the future has the time travel technology to send a terminator cyborg back in time, wouldn't they have the technology to reverse the process and send the cyborg forward in time to the future?

I think you inadvertently answered your own question by acknowledging that the future AI (Skynet/Legion) is "sending" the terminators to the past. As Ellison Havelock mentioned, there is no established method for the machine in the future to reach into the past and pull something back through time.

@Ellison Havelock said:

Skynet only sends units back in 'read only mode' to prevent them from deviating from their mission in any way.

I haven't watched the first couple movies in a long time, but I only remember the idea reiterated in this movie that a Terminator cannot deviate from its primary objective. Carl's was obviously to kill John, which he completed. I could be wrong as I'm not a Terminator expert, but I don't remember any information about 'read only' and 'write date' modes ever being established in this franchise.

@poit57 said:

@Ellison Havelock said:

Skynet only sends units back in 'read only mode' to prevent them from deviating from their mission in any way.

I haven't watched the first couple movies in a long time, but I only remember the idea reiterated in this movie that a Terminator cannot deviate from its primary objective. Carl's was obviously to kill John, which he completed. I could be wrong as I'm not a Terminator expert, but I don't remember any information about 'read only' and 'write date' modes ever being established in this franchise.

This is in the T2 Special Edition cut. There is an added scene which was not in the theatrical cut, in which Arnie explains that he, like all units sent back, was set to 'read-only' and cannot learn or adapt his programming. This discussion comes about when John advises Arnie that he needs to learn to be more human, but Arnie cannot. It actually forms a major character arc for John, Sarah, and the T-800. It's a very powerful scene, and adds to the understanding of Arnie's final line, "I know now why you cry, but it's something I can never do."

I recommend very fervently that you track down the T2 Special Edition and give that a watch, along with re-watching the original Terminator from 1984. Again, T2 never should have been made, according to the story of the first film, but it's still a very well-made and entertaining movie, and it does lay some groundwork which illustrates that Dark Fate has an unworkable story.