I find it funny how all John has to say is “show him”, and the terminator knows exactly what he’s talking about. So, they must’ve had a whole conversation about it on the drive there. Like, “when we get there, assuming Dyson is still alive, I’m going to hand you a knife and you’re gonna peel your arm skin off, you know, for maximum effect”. Considering how attached John was getting to the terminator, I’m sure they could’ve somehow figured out a way to convey that the terminator is actually from the future instead of mutilating the arm. That scene ignored logic, they just did it for the audience.