McG confirms a darker cut of Salvation exists.

Closer to the R rated tone of the prior films.

"It's interesting because I feel like we did so much right with Terminator but, ultimately, got just enough wrong that we got beat up a little bit by the fanbase and it really, really broke my heart. And now, strangely, I think the film has started to age better. And there is a different cut: I have my own cut of that film and there's people online that talk about wanting to see that cut. And that's interesting! But I think I got a lot of things right with that."

https://movieweb.com/terminator-salvation-directors-cut-mcg/