10 Ways Movies Blew Your Mind Without You Even Realising

8. Linda Hamilton's Twin Sister Was Used For Her T-1000 Double - Terminator 2: Judgment Day

Terminator 2 is one of the greatest "visual effects movies" of all time, precisely because James Cameron understood the importance of allowing CGI to enhance the practical, human elements of a story, rather than ever letting them supersede the vital tactile element.

Yet T2 is such a well-aged triumph of VFX mastery that any remotely complex sequence can be easily dismissed as another feat of ahead-of-its-time visual wizardry.

This is especially true with the climactic sequence where Sarah Connor (Linda Hamilton) faces off against a doppelganger of herself created by the T-1000 (Robert Patrick).

Though most would assume that some sneaky split-screen trickery or primitive face-replace tech was responsible for the scene, Cameron instead took full advantage of the fact that Linda Hamilton had a twin sister, Leslie, who could be used to create a practical double of Sarah.

If you look at the two actresses in the same shot, as above, it's actually relatively easy to tell the two apart, but in the thrall of the movie itself, you'd never have a clue.

In fact, Leslie is also used for the nightmare sequence featuring two Sarahs, and most ingeniously of all, she also doubles for her sister during the incredible Special Edition sequence where the T-800 (Arnold Schwarzenegger) has its chip reconfigured in front of a "mirror."