The studios had long wanted to make a sequel to the previous Terminator films, but for a long time Arnold Schwarzenegger refused to do it unless James Cameron was directing. Cameron eventually told his friend to "just do it and ask for a shit-load of money," reasoning that the character was as much Schwarzenegger's as it was his. Schwarzenegger confirmed this in a talk-show interview, saying that when he asked, Cameron told him to "take the money and run".
Edward Furlong was originally supposed to reprise his role as John Connor. However, in December 2001, it was reported that he had been dropped from the film, allegedly due to a substance abuse problem. He was replaced by Nick Stahl shortly before filming began in April 2002. He later said, "It's the growing pains of me. I was part of the project and had a very nice deal but then I guess to celebrate I went out and overdosed on coke and kind of destroyed that whole thing. But I learned my lesson and I'm back on track."
(at around 42 mins) The gas station at which the Terminator stops for refueling is the same gas station seen in all three Terminator movies. In The Terminator (1984) it was shown at the end where the pregnant Sarah stops before driving to the Mojave Desert. In Terminator 2: Judgment Day (1991) it is where Sarah camps in for the night after she escapes from the hospital.
Arnold Schwarzenegger worked out for six months, about three hours a day, before shooting started, by which time he said he had the exact same body weight and muscle measurements as he had 12 years previously while shooting Terminator 2: Judgment Day (1991).
Arnold Schwarzenegger's fee for reprising his role was $29.25 million, a record at the time. His contract was 33 pages long and written by Hollywood super-lawyer Jacob A. Bloom between June 2000 and December 2001. It was written into the contract as a "pay or play" fee, meaning he would get paid whether or not the movie was made. His "perk package" included a lump sum of $1.5 million for private jets, a fully equipped gym trailer, three-bedroom deluxe suites on location, round-the-clock limousines, and personal bodyguards. He also insisted on, and got, 20% of the gross receipts made by the venture from every market in the world-including movie theaters, videos, DVDs, television licensing, in-flight entertainment, game licensing, and so forth-once the movie had reached its cash break-even point. Such "contingent compensation" is not unusual in movie contracts, but, in most cases, Hollywood accounting famously uses smoke and mirrors to make sure to define "break-even" in such a way that a movie never reaches it. Schwarzenegger also could decide who worked with him. The contract "pre-approval" clause gave him choice of not only the director (Jonathan Mostow) and the principal cast, but also his hairdresser (Peter Tothpal), his makeup man (Jeff Dawn), his driver (Howard Velasco), his stand-in (Dieter Rauter), his stunt double (Billy D. Lucas), the unit publicist (Sheryl Main), his personal physician (Dr. Graham Waring), and his cook (Steve Hunter). The negotiation of this contract did not come cheaply. The legal and accounting budget for the movie was $2 million. By the time all of Schwarzenegger's demands were met, the budget of the film had risen to $187.3 million, making it the most expensive independently produced movie in history.