Stipulating that time travel plot lines rarely hold up to logical scrutiny, and also that TDF isn’t even probably in the top 20% of those in terms of intelligence …
What future did Schwarzenegger’s “Carl” character come from?
(Spoiler: early in the movie, we see a flashback of an Arnold-style terminator killing a young John Connor. Later, in the “present,” this terminator is living a quiet life as a drapery installer. For real.)
OK, so in T2, Sarah and John Connor, with the help of the good Arnold terminator, destroy the evil terminator and all the Cyberdyne technology (including the good Arnold terminator) that leads to Skynet and the creation of the terminators. So … no Cyberdyne, no Judgement Day, no terminators. That future is cancelled.
In TDF, we learn a different company somewhere in the non-Cyberdyne future has created a new AI weapon that, like Skynet, wants to kill all humans etc etc. From that future we get the enhanced human Grace and the new, slicker-than-ever terminator.
Sarah says she’s been killing terminators all along, so presumably they come from the new, non-Cyberdyne future. But what future does Carl come from? He can’t come from the old Cyberdyne future because it doesn’t exist anymore, and it seems pretty unlikely the new AI would just happen to create an identical terminator to terminate a hero who, logically speaking, isn’t even necessary anymore (since the future he will impact has already been cancelled).
Was he an earlier edition of the original movie’s T1 who just happened to arrive later in Sarah and John’s chronology?