Besides saying fukk and people burning in Sarah Conners dream what other parts would give it an R rating?
I can think of a few things. The T-1000 throwing the huge sword blade through Jon's foster dad's milk carton, into his mouth, and out the back of his head. The T-1000 turning his finger into a giant needle and stabbing that cop through the eyeball and out the back of his head, and they showed the guy shaking and convulsing. The guard in the mental hospital licking Sarah Connor's face. Those weren't even that bloody, but I don't think they'd show those angles and keep the camera on them in a modern PG-13 movie.
Sarah beating the shyt out of everyone with the billy club, and there was some solid blood spray and maybe some teeth knocked out. Arnold slicing his forearm and ripping it off to show the metal arm.
That dude getting lit up in the hallway when the T-1000 starting emptying the clip at Jon and Arnold, and there were a lot of bloody exit wounds. The T-1000 super shiving/impaling that truck driver. Dyson got bloodied up by the SWAT team when they shot all those submachine guns, and earlier when Sarah popped him with the .45 in front of his wife and kids. The nuclear missile landing off in LA.
That's mostly what I can think of. it wasn't bloody, but the T-1000 stabbing Sarah in the shoulder and twisting it so she would give up Jon in the molten metal factory.
A lot of that stuff is pretty tame looking back but I also think we've been desensitized to a lot of shyt over the years.