Terminator 2: Judgment Day (1991)

T2 is one of those rare sequels that might be better than the original, at least as entertainment. The action is relentless and the liquid-metal Terminator was a genuine milestone in special effects. The science, though, is even shakier than the first film. Where does a liquid-metal robot get the energy to reshape itself? How does liquid metal think? And the time travel now contradicts the first film - in The Terminator the future can't be changed, and in T2 it can. You can't have it both ways! But the core warning, about building an AI and giving it control of our weapons before we understand it, has only become more relevant.