I have only watched the pilot episode so far, but I had one major problem with it. (Insert obligatory "You have no problem with time-travelling killing machines but you have a problem with X?" comment here.)
The Terminator that had the gun hidden in its thigh cavity. Why would SkyNet go through the trouble of putting that cavity in there and sending the machine back, knowing it would ruin its disguise when it had to cut the thing out? Now, I can see the trade-off if it was a high-tech weapon, but I think it was a Glock! Why even bother?
After seeing the original movie, a friend of mine and I discussed why they didn't stick a plasma rifle through a cat, as the cat might live long enough to make the trip. With some surgery, they could ship a whole arsenal inside of a cow. The earlier Terminator comics by Dark Horse covered this concept years ago, but after we had already come up with it.
What they did in the comic was cut open the human tech that remained behind to operate the time platform, stuff a laser pistol inside of his gut, cauterize the wound, then ship him back with the Terminators that were sent back to pursue the humans that had already gone through.