Caution: Spoilers ahead for Terminator: Dark Fate
Terminator movie. A string of other actors including Christian Bale and Jason Clarke have played John since, but Furlong remains the name and face most closely associated with humanity's heroic savior.
Reuniting the Terminator franchise with both James Cameron and Linda Hamilton for the first time since 1991, Dark Fate picks up almost 30 years after the famous sequel, writing the more recent Terminator movies out of existence. With Sarah Connor's return, however, it became necessary to for John's presence in the story. Edward Furlong had previously teased that he would have a small role in the Terminator movie, and he certainly wasn't lying about his limited contribution to the film, with only the actor's face making it into the finished cut.
During an early scene, Terminator: Dark Fate reveals that, following the events of Judgement Day, Sarah and John were in hiding on a beach resort, and had seemingly relaxed a little since the paranoid days of yore. As John attempted to smooth-talk some of the local ladies at the bar and Sarah watched on in contentment, an Arnold Schwarzenegger 101 series Terminator emerged from the future and finally succeeded in assassinating John Connor for Skynet, leaving his mother devastated.
The John Connor seen in Terminator: Dark Fate is only slightly older than the one seen in Judgement Day and appears alongside a younger Sarah Connor from the same era, but neither actor actually appears in the scene. Instead, the pair are played by body doubles, with digital likenesses grafted onto their faces. While Hamilton's casting allowed her to be on-set during the filming of the flashback sequence, Furlong himself didn't return for the role. Connor was played by body double Jude Collie, and Furlong's image was plastered on Collie's face using CGI, giving the impression of John Connor as he first appeared in 1991.
Although the effect sounds like a potential mess in the style of Henry Cavill's erased mustache or the digital baby in Twilight, the cameo comes off relatively well, and doesn't feel as jarring or visually out of place as it might've done given the technical challenge involved. The John Connor appearance in Terminator: Dark Fate succeeds in resolving the character's fate and removes him from the equation ahead of the film's main story, while also neatly establishing Sarah's tragic past.
Some might question why Terminator: Dark Fate would opt for the body double route, rather than the more common digital de-aging that has become fairly commonplace in the Marvel franchise and elsewhere. While this would've likely been possibly in Linda Hamilton's case, de-aging Furlong (currently in his 40s) back to a teenager might've stretched the technology beyond its limits, necessitating the use of a double. Having settled on this technique for John, it makes sense to keep the scene consistent and do the same for Sarah, even though Linda Hamilton perhaps would've been easier to de-age.
