28-year-old Linda Hamilton playing 19-year-old Sarah Connor.
Also, 27-year-old Michael Biehn playing 21-year-old Kyle Reese.
Defictionalization: The British Ministry of Defence launched a network of communication satellites to coordinate between NATO, EU and British forces. Guess what they called it...
Dueling Movies: Runaway, a film also about robots and starring Tom Selleck and Gene Simmons (and written/directed by Michael Crichton), was projected to be the big sci-fi film of 1984. Who would have thought that it would be overshadowed by a low-budget film, with B-list actors, written and directed by an unknown who got the idea while having a fever? Not to mention one actor was mostly a theater actor (Biehn), the other one was a body builder with a thick accent who had more bad movies than good ones then (Arnold), and Cameron only had one directorial credit to boot before doing The Terminator: the film Piranha Part Two: The Spawning.
OJ Simpson was originally considered for the role of the Terminator. The studio did not go with this casting choice because they could not see a nice guy like OJ playing a killer.
German actor Jürgen Prochnow, known for his role as the Captain in Das Boot, was also considered for the part. Hilarious in Hindsight, as he ended up playing Arnold in See Arnold Run (a film about Arnold's run for governor of California).
One of the concept art showed a T-800 skeleton crawling after Sarah with a butcher knife.
The film was actually meant to end with the tanker explosion and Reese living through the movie. But Cameron found this too anti-climatic and rallied for the factory ending. He won out leading to the much more Bittersweet Ending.
Arnold Schwarzenegger himself was originally considered for the role of Kyle Reese (the hero) while Lance Henriksen was the original choice for the Terminator as Cameron originally envisioned the killing machine as having a more ordinary appearance in order to blend in with the rest of society, but changed his mind when he met Arnold and felt that he was in the presence of "a living machine".