The trick with keeping a shotgun attached around the arm that Marcus shows Kyle Reese, is used by the older Kyle Reese played by Michael Biehn at the beginning of the original The Terminator (1984), after he saws off the butt to shorten the shotgun he stole from the police squad car.
Director McG asked the cast and crew to read the novel "The Road" by Cormac McCarthy and "Do Androids Dream of Electric Sheep?" by Philip K. Dick - the basis for Blade Runner (1982) - because he wanted them to absorb the bleakness of the world in the novels.
Director McG actually went to visit James Cameron who was working in New Zealand on Avatar (2009) to gain insights and respecting the mythology set in the first two films. It was during there that Cameron recommended his art director Martin Laing to work as a production designer and Sam Worthington to play Marcus.
During filming in the summer of 2008, Christian Bale yelled and used profanity at cinematographer Shane Hurlbut, who was adjusting the light in the background while Bale was doing an intense scene and got distracted by the cinematographer. Bale's tirade was then leaked on the Internet. After it was leaked, Bale publicly apologized for his remarks and insisted that he and Hurlbut are on good terms.
Earlier drafts of the script before rewrites focused a lot more on just Marcus Wright and Kyle Reese, with John Connor making an appearance in the last few scenes. Christian Bale was first offered the role of Marcus but took more interest in the character of John Connor so rewrites took place to give him more of a substantial role throughout the film.
Was intended to be the first of a new Terminator "Future War Trilogy", all done by McG, but the films poor performance and reception led to McG being fired and replaced before the next two films ever came to fruition. Instead, a new trilogy is planned to begin with Terminator Genisys (2015).
The third Terminator film to have the line, "Come with me if you want to live." In The Terminator (1984), Kyle Reese says it to Sarah Connor at the Tech-Noir club. In Terminator 2: Judgment Day (1991), the Terminator says it to Sarah Connor when they first meet at the mental institution. In 'Salvation' Kyle Reese says it to Marcus Wright when they first meet. In Terminator 3: Rise of the Machines (2003), a paraphrased version of this line ("Do you wanna live? Come on!") is spoken by John Connor to Kate Brewster when he and the T-850 rescue her in the graveyard. "Come with me if you want to live" is also spoken by Cameron in the pilot episode of Terminator: The Sarah Connor Chronicles (2008), when rescuing the teenage John Connor from the 'Cromartie' T-888.
The first recording that John Connor listens to of his mother is an edited version of the recording that she makes at the end of the first Terminator. Moments before the picture that he has and eventually gives to Kyle Reese is taken.
Just before Connor sets down his helicopter to infiltrate the research facility, the target camera of an incoming rocket indicates the facilities location to be N36° 17'39'' E117° 15'25''. According to these coordinates the facility is located in China, approximately 350km south of Bejing. (See also Goofs)
Christian Bale later stated that before the film, he expressed the same concerns to McG that the Terminator fan-base was expressing about him taking over the franchise. Bale told him that "Nothing in your (McG) filmography suggests that you have what it takes to do this movie properly." McG ultimately convinced Bale to give him a chance so he could "evolve" as a director, but as of 2014 admits that the film "didn't work", insinuating that it was ultimately McG who blew it, and stating that he would never work with McG ever again, though he wishes him well.
Assuming there is small margin of error between the "correct" and "alternate" time lines of the previous films, this installment takes place about 11 and a half years (2018) before the events leading up to the first (2029).
The river bank used for the napalm strike during Marcus' escape was part of a one-mile man-made river because environmental officials present during the production will not allow them to use the existing river.
The song that plays when Marcus Wright starts the truck in LA is 'Rooster' by Alice in Chains. The song was written by guitarist Jerry Cantrell about his father's experiences in Vietnam (Rooster was Jerry Cantrell, Sr.'s nickname), and the opening line, "Ain't found a way to kill me yet" parallels the movie from John Connor's perspective, with the machines as yet unsuccessful in their numerous attempts to kill him.
In early 2008, Paul Haggis was brought on to polish the script. After he was done, three weeks before filming, Shawn Ryan was asked to rewrite the script, and he took "a pretty big whack" at it. However, he later had to return to television, and the filmmakers "subsequently brought in one or two other writers to continue the work," most likely Anthony E. Zuiker and Jonathan Nolan. So extensive were the rewrites that Alan Dean Foster decided to rewrite the entire novelization after submitting it to his publisher, because the compiled shooting script was very different from the one he was given beforehand.
John Connor and Marcus both use a Sony UX which is the small hand-held PDA device they receive information through and use as an interface to some of the systems, this is a micro PC with a 4.5in screen and weighing just over 1lb.
This is the first film in which John Connor and his father Kyle Reese have appeared together (if one disregards the Special Edition of Terminator 2: Judgment Day (1991), where Kyle Reese makes an appearance in a dream sequence that was deleted from the Theatrical Version).
In the opening scene, Marcus is executed by lethal injection using a very accurate prop based on the execution machine developed by engineer Fred A. Leuchter Jr.. As of the release date, this system is only used by four states, mostly due to problems adapting the drug delivery rate for different individuals.
At one point, the film carried the subtitle "The Future Begins." Coincidentally, the film Star Trek (2009) (which opened weeks before Terminator Salvation (2009)) used the same saying as a tagline. Actor Anton Yelchin appears in both films.
Each Terminator film has been produced under a different company. The Terminator (1984) was produced by Hemdale and went through Orion, Terminator 2: Judgment Day (1991) went through Carolco and Tri-Star (which was owned by Columbia), Terminator 3: Rise of the Machines (2003) was produced by C-2 Pictures and distributed through both Warner Bros. (Domestic release) and Columbia Pictures (international release), and Terminator Salvation (2009) was produced by The Halcyon Company and distributed through both Warner Bros. (Domestic release) and Columbia Pictures (international release).
The film's look is based on Technicolor's OZ (Olson-Zacharias) process, which adds three times more silver to the negative film stock, making it milkier without affecting the grain structure. Although the process was tested in pre-production, it wasn't actually used. Instead, its look was mimicked in the digital intermediate process.
This was originally intended to be the second half of the two Terminator movies developed back to back by Mario Kassar and Andrew G. Vajna. It was originally titled Project Angel (seen in some computer screens in Skynet during sync sequence with Marcus) and was to be written by David C. Wilson for release in 2003 with the events to start immediately after the first-half, which was Rise of The Machines. However, actor commitments including Arnold Schwarzenegger's office term as Governor of California prompted the script to be rewritten, including moving the time line by credited writers, John Brancato and Michael Ferris, to be supervised and directed by Jonathan Mostow. The project was delayed because in 2006, Kassar and Vajna decided to end their partnership and the movie rights was sold to Derek Anderson and Victor Kubicek.
In the intro, the camera focuses on each letter of the film's title before the words "Terminator" and "Salvation" intersect with each other before being placed in their appropriate places, is similar to the intro from The Terminator (1984).
The silver-looking machine where the nuclear fuel cells are stored at the Skynet factory is actually a piece of equipment from a semiconductor manufacturing plant, an SVG 90-S coater/developer for silicon wafers.
The shotgun Kyle initially has and is taken away from him by Marcus is a Mossberg 500 typically used for door breaching. Standoff muzzle devices set breaching shotguns apart from the rest and the giveaway feature.
The trivia items below may give away important plot points.
Near the end of the movie, there's a confrontation with a newly-minted Terminator with Arnold Schwarzenegger's face. However, Schwarzenegger didn't shoot anything for this movie; the effects team scanned his face from a previous film and applied the result to the stunt double. The result is a character with a much younger face than Arnold possesses today.
This is the first "Terminator" movie in which a character does not speak the word "Terminated" after killing a Terminator (i.e. "You're terminated!"). However, the word "Terminated" flashes in red on the T-800's internal processor after it thinks it has killed Marcus Wright, a Terminator with a human brain and heart.
A similar desert gas station appears in all four Terminator films. In The Terminator (1984) Sarah stops at one before driving to the Mojave Desert. In Terminator 2: Judgment Day (1991) Sarah, John and the T-800 camp in one for the night after she escapes from the hospital. In Terminator 3: Rise of the Machines (2003) it is where The T-800 stops for supplies and gas. In Terminator Salvation (2009) it is the hideout for the refugees shortly before they are attacked by the Harvester Terminator.
During the final encounter, the T-800 picks up a concrete block and repeatedly bashes it into Marcus' chest. This is reminiscent of Terminator 2: Judgment Day (1991) where the T-1000 uses a steel girder in a similar manner, crushing the T-800's head and chest area.
All four 'Terminator' films have had their climactic battle scenes take place in industrial settings. The Terminator (1984) saw Kyle and Sarah face a skinless T-800 in an automated factory; Terminator 2: Judgment Day (1991) had the T-800 and the T-1000 face off in a steel mill; Terminator 3: Rise of the Machines (2003) placed John, Kate and the T-850 at Cyber Research Systems, where John and Kate escaped the TX in a particle accelerator; and Terminator Salvation (2009) sees John and Marcus face off with the very first T-800 in a Skynet factory.
In one scene, moto-terminators attack a semi-tow truck driven by Kyle Reese, Marcus Wright and Star as they try to fight the machines off. This is a reference-in-reverse to Terminator 2: Judgment Day (1991), where the T-1000 drives a semi-tower, chasing the young John Connor on a dirt bike. Also, the moment where the moto-terminator jumps off the bridge and lands in front of the tow truck is a reference to the T-800s jump into the canal in T2: the T2 stunt was originally planned to happen the same way but was changed due to safety and budgetary issues.
John Connor dumps molten steel over a Terminator and then freezes it at the climax. This references Terminator 2: Judgment Day (1991), when the T-1000 was frozen by liquid nitrogen and then thawed out by molten steel at a steel works.
Originally the ending was to have the real John Connor die and someone else, likely Marcus, take up the mantle and assume Connor's identity since very few people actually knew what the real John Connor looked like in 2018. The idea being that anybody could be a hero (in this case, John Connor) and that not only is Judgment Day inevitable, but John Connor and more importantly, the Resistsnce is as well. Sadly, this idea was scrapped when the script was leaked.
John Conner asks Blair Williams "How's that leg ", she says "I'll Live". In Terminator 2: Judgment Day (1991) at the mental hospital, the T-800 shoots the security guard in the leg and says "He'll live".