The early scenes of T-1000 (Robert Patrick) being the villain was intended to be a twist at all. The T-1000 now stands as one of the most iconic cinematic villains ever, after all.
Hindsight aside though, director James Cameron indeed intended to keep the audience guessing as to character alignments for the first part of the film. For example, look at the T-1000's introduction scene. While the music that plays over it is fairly ominous, the way it's shot fully disguises the character's liquid metal nature. Based on what is shown, it could easily be interpreted that he simply punched the cop in the gut then stole his clothes, before searching for John in order to protect him from Arnold Schwarzenegger's once again villainous T-800.
It's not until John (Edward Furlong) is caught between the two cyborgs that the truth is revealed onscreen: the T-800 model that targeted his mother is now his protector, and the seeming policeman who'd been looking for him is the real enemy. However, Terminator 2 does drop several hints to this twist beforehand.
How Terminator 2 Foreshadows The T-1000 Twist
In contrast to the T-1000's opening scene, in which things are kept somewhat ambiguous as to exactly what the new character did to the one man he encountered, the T-800's introduction sees his wreak havoc at a bar, tossing around patrons who refuse his request for clothes and transportation. However, it's very clear that the T-800 doesn't kill anyone, whereas in the first film, he shows no hesitation about killing whoever gets in the way of his objective. This is a clue that he might not be the bad guy this time.
Additionally, when the T-1000 initially questions John's foster parents about his whereabouts, it's revealed that the T-800 visited them prior, yet both were left unharmed. During this scene, John's dog Max is barking quite loudly, and since dogs can detect Terminators, it's a clue that the T-1000 isn't human, which again, had not been confirmed onscreen as of that point. Obviously, once the mall fight happens, all pretense is out the window, and the character alignments are clear.
It may be tempting to look back and wonder how anyone might not have immediately realized that the T-1000 was a villain, but it's important to that audiences only knew Arnold Schwarzenegger's Terminator as a brutal killer out to prevent John Connor's birth, so why would anyone think he would suddenly be the hero in the sequel? Well, outside of those who saw some of the trailers and TV spots for Terminator 2, which readily spoiled the twist, proving trailers that reveal way too much are by no means a recent invention.
