In The Terminator, Lance Henrikson was originally supposed to play the machine and Arnie was going to be Kyle Reece, but it was Arnie that convinced James Cameron that he should get the role of the machine.
The movie with Cage and Travolta was supposed to be a movie with Schwarzenegger and Stallone, rumors say they hated each other back then and Sly was not happy about it.
In The Terminator, Lance Henrikson was originally supposed to play the machine and Arnie was going to be Kyle Reece, but it was Arnie that convinced James Cameron that he should get the role of the machine.