Avengers: Endgame utilized time travel. The Marvel Cinematic Universe's biggest film and the installment from the Terminator franchise both incorporate the concept of warping through time in their their respective narratives. They do it in very different ways, and Miller why there's a reason why they stuck with how they did it in their movie.
Following the catastrophic ending of changes resulted in multiple splintered timelines in order to preserve what already took place in the primary universe.
During Dark Fate's movie at this San Diego Comic-Con which Screen Rant attended, Miller openly spoke about his love for Marvel. But despite that, he its that he isn't a fan with how Endgame used time travel because it cheapens its franchise's impact with a few realities involved. He used this opportunity to compare it to the Terminator film series which has a singular timeline.
"I loved Endgame however time travel with multiple realities loses some stakes. So in the Terminator universe, there is only one timeline."
Endgame made sure to hammer on the public that the movie is executing time travel different from how it's widely known in media - they even referenced several other movies that utilized the concept and squashed how they all got it wrong. There's actually scientific basis on how Marvel Studios tackled the idea, still, given that it's fictional it will always be up for debate. On top of that, there are a couple of lingering questions on how few things were made possible considering how they framed time travel. Making it more muddied is the fact that even the Russos and writers Christopher Markus and Stephen McFeely failed to agree on how it would actually work in the film. In any case, the general public was willing to look past these loopholes in exchange for a rather entertaining film.
Whether or not MCU's time travel checks out remains to be seen as it's ultimately in the hands of Marvel Studios to ensure that it makes sense moving forward. As of now, fans are just thrilled with what Avengers: Endgame offered them. Miller's comments on stakes has some credit to it, but the Russos were able to balance it out with huge sacrifices from some of the franchise's beloved superheroes. As for Terminator: Dark Fate, fans know that it will directly deal with the ending of Terminator 2 particularly with Sarah Connor's decision to destroy Cyberdyne Systems. The Terminator film series' timeline has always been confusing, but it will be interesting how this new installment potentially impacts the way things panned out in the franchise as a whole. At the end of the day, since a fictional concept, films and shows can use time travel any way they want just as long as they're able to sell it properly.
