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 by that point (Arnold), and Cameron only had one directorial credit to boot before doing Terminator - Piranha 2.
What Could Have Been / Hilarious in Hindsight: 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).
Throw It In: The T-800 inexplicably saying "I need a vacation...", but James Cameron found it so funny he left it in.
In addition, Sarah Connor knocking out the orderly with a broom, as well as the resulting injury, was indeed real. She, or rather, the actress, did it out of revenge because in an earlier scene the orderly went a bit too easy on her during the acting. They kept it in for the final cut (no pun intended).
Shaquille O'Neal reportedly asked for a role as a black Terminator.
Michael Biehn was originally supposed to be the T-1000, but the studio thought this would be too confusing.
Terminator 2 3-D: Battle Across Time
Doing It for the Art: In the behind-the-scenes documentary, Cameron goes to great lengths about how he is essentially treating the attraction as a third Terminator movie.
The Other Darrin: Kimberley Duncan is played by different actors from show to show, and each one has a different take. For example, one acts a lot like an Excited Kids Show Host, another tends to say "Super!" a lot.
What Could Have Been: Another portion of the fanbase would have prefered the original ending, with John Connor dying, and Marcus taking over his place, over the implausibility of the one that ended up being filmed.
Definitely more plausible though than John's skin being successfully grafted onto Marcus without looking weird, considering how Marcus' skeleton is shaped COMPLETELY DIFFERENT than John's. Think of the alien Big Bad's disguise in the first MIB movie.
Not to mention that John Connor was supposed to "trick" Kyle Reese into falling for Sarah Connor and fathering him. He told him stories about her. How is Marcus supposed to fulfill that role?
Arnold also had to get back into bodybuilder-level shape to play the T-850 in the third one.
The Other Darrin: John Connor has been portrayed by many people; T4 also has a new Kate Brewster and Kyle Reese; understandable and necessary in the latter case, since he's several years younger than in the original film.
