- Billing Displacement: Despite prominent billing, Helena Bonham-Carter only gets five minutes of screentime.
- Cast the Runner-Up: 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.
- Deleted Role: Terry Crews played Jericho, a resistance soldier and brother to Barnes, in a deleted scene which never was included. Similarly, Greg Plitt's brief role as a hybrid similar to Marcus was deleted after a general plot change.
- Deleted Scene: There were many scenes that didn't make it to the screen, (some of which were in the trailer), including (see What Could Have Been as well):
"The future is not set. Ive been told I said that once. Many years from now. It was a warning. That I was going to hell. But if I fought hard enough, I could escape. I believed it for a lifetime. Now I pray I was wrong. Because now I am in hell. We all are. And the future I used to dread is the only hope I have left."
- An opening narration by Connor:
- The original cut of the film included a topless scene when Blair and Marcus are warming themselves by the fire. Director McG said that it was meant as a Shout-Out to Kelly McGillis' topless scene in Witness, but that it ultimately felt exploitative and would have flouted a PG-13 rating. The scene is reinstated in the director's cut Blu-ray.
- A longer third act, that had John and Kate having a longer conversation before he leaves on the mission to rescue Kyle, appearances by T-700's, more footage of Marcus infiltrating Skynet, prisoners escaping during the attack, the T-800 trying to use the T-600's minigun and Kyle burying Marcus and finding Sarah's Polaroid in John's jacket.
- Disowned Adaptation: After Terminator: Dark Fate's production, this film is one of the three Terminator movies that is completely turned away by James Cameron.
- Fake American:
- Franchise Killer: The plans for any future endeavors with this incarnation vanished at some point and prompted another reboot that reset the Terminator playing field altogether; Bale was not invited back, but Schwarzenegger was. (Ironically, said reboot, Terminator Genisys, ended up being a Franchise Killer too.)
- Hostility on the Set: During production, Christian Bale infamously went off on a furious and profane rant directed against director of photography Shane Hurlbut, telling him to get off the set because he was blocking the shot and calling him unprofessional. The audio of the incident went viral and memetic to the point where it was remixed into a Stupid Statement Dance Mix. Bale later issued an apology.
- In Memoriam: The film is dedicated to Stan Winston.
- Old Shame: Christian Bale admitted that he turned down the role of John Connor at least three times before signing on and only accepted to prove that he could bring something to the role. Bale ultimately regrets his now infamous on-set rant and was ashamed the film failed to reignite the franchise.
- Prop Recycling: Of sorts. Recreating the face of a younger Arnold Schwarzenegger was made possible thanks to moldings of his face that were preserved since The Terminator. Those served to create the animatronics back in the day.
- Separated-at-Birth Casting: Anton Yelchin was uncanny as a young Kyle Reese, originally played by Michael Biehn.
- Troubled Production: The script of the film was extensively rewritten at least three times, both for Bale's Executive Meddling and testing audience's reactions. Then filming was delayed for four months when Helena Bonham-Carter lost members of her family in a car crash and had to attend to her relatives in England.
- Uncredited Role: Linda Hamilton recorded Sarah's messages herself uncredited.
- Viral Marketing:
- Wag the Director: Christian Bale was offered the part of Marcus, but wanted John Connor. This expanded the role, and kind of threw things off-balance. Of course, the most infamous case involving Bale was the rant he delivered at the DP. In the leaked audiotape, Bale chews out the director of photography for changing the lighting levels while he was in the midst of performing a scene, and subsequently tells McG that he will not have it happen again.
- Of course Bale would later go on to apologize for the rant sometime later of his own violition. And most Cast and Crew reaction when asked about it was "You don't change the lighting during a scene".
- What Could Have Been:
- In an early script, Marcus was much more emotional and talkative, just like Kyle and a non-mute Star, and they would encounter cannibals in the road and not a good-natured clan of survivors. Marcus would be revealed to be a just brain in a fully cyber body, just like Serena Kogan, who would rexplain Skynet was creating hybrids like them to build a new, superior human society as part of what they called Project Angel. John Connor himself wouldn't appear personally until the last act, and more shockingly, he would be killed by Serena while rescuing Kyle, so Marcus would assume his role by surgical methods to lead the resistance.
- Even after turning John into a main character by Bale's demand and adding the Ashdown subplot to fit it better into the story, the main plot points were kept when they started shooting: Helena Bonham-Carter was going to play the cyborg Kogan and not just her image used by Skynet, Marcus would have fought a T-800 in his meeting with her, and his impersionation of a dead John was going to be the official ending. However, this ending was blasted by everyone who heard about it after an internet leaking, with McGs himself finding it thoroughly wrong upon reading it, and the Project Angel storyline was felt as too outlandish and out-of-character for the franchise, so they changed plans again mid-production. Some scenes from these earlier ideas were shot and are contained in the DVD.
- There was even a second alternate ending where Marcus, after waking up from the operation, turned evil and killed everyone in his hospital room, including Kyle, Star, Kate and Barnes. It got as far along as having concept art drawn up for it, but was even more hated than the former and was eventually discarded.
- Stan Winston was intended to have a cameo as a prisoner who was fighting a Hydrobot in the Skynet research facility, but this was scrapped due to Winston's worsening health.
- The submarine commanded by Ashdown was originally going to be destroyed by an underwater Harvester and not by a simple missile.
- Had Arnold Schwarzenegger not given permission for his likeness to be used for the T-800 that attacks John Connor in the factory, the plan was to have Connor shoot the T-800's face off as the camera panned up.
- Josh Brolin turned down the role of Marcus Wright.
- Tilda Swinton was originally cast as Dr. Serena Kogan.
- The Wiki Rule: The Terminator Wiki.
- You Look Familiar: Michael Papajohn, who played a paramedic in Terminator 3: Rise of the Machines, appears in this movie as Carnahan, the leader of the gang who harasses Blair.
Trivia / Terminator Salvation