From early pioneers like Tron and Terminator 2: Judgment Day, to game changers like Episode 1: The Phantom Menace and The Matrix trilogy, CGI has been used to augment the ideas and themes presented in science-fiction films. Science fiction as a genre provides different perspectives on how we think of everything from the future of our race, to the perils of technological advancement and the complexities of space travel. Computer graphic imagery and the advancements in that field help filmmakers realize their visions in ways that weren’t possible with practical effects alone.

These days, CGI is more prevalent in science-fiction films than ever before. We’re used to seeing the big spectacle of space battles in the latest Star Wars film. We’ve become accustomed to the exotic aliens of Star Trek films. But what about when CGI is used so subtly you don’t even notice it? Or for things other than giant spaceships and strange extraterrestrials? Below you’ll find ten things in sci-fi movies you didn’t know were CGI.

Star Wars: The Force Awakens

Sometimes the CGI in sci-fi films is used not for huge battles or giant creatures, but to fix mistakes or recreate common objects. CGI has become a staple in the latest Star Wars films, especially for obvious things like ships, planets, space. But it was also used rather subtly and to great effect in The Force Awakens.

The dialogue between Supreme Leader Snoke and Kylo Ren about Ren really being Ben Solo, Han Solo’s only son, was meant to be later on in the film. Therefore, it was filmed with Ren’s helmet off. JJ Abrams decided the reveal should come sooner, and the scene had to be reshot, with a CGI mask placed over Adam Driver’s face. You can’t tell it isn’t a real helmet.

Deus Ex Machina

Deus Ex Machina is a genre film that relies more heavily on ideas than visual effects, as implied by the nature of its title, which implies a plot contrivance. Alicia Vikander stars as the cybernetic artificial intelligence unit that is created by the minds of a brilliant programmer and a Dr. Frankenstein-like engineer.

While in many scenes it appears Vikander is wearing some sort of suit that might simulate her cybernetic bodyform, she isn’t. Only her face, hands, and feet are her own; everything else is CGI. It moves with such synchronicity to her own body movements as to appear virtually indistinguishable.

E.T.

One of Spielberg’s landmark films, E.T. didn’t make a flashy use of CGI in 1982, with the renowned filmmaker electing to use puppetry and practical effects wherever possible (save of course for the iconic bicycles-to-the-moon-shot). All bets were off when it came to the 2002 DVD release, however.

Spielberg had often said that if he could go back and “fix” anything in the film, it would be the guns used by the police who go after the escaping kids. He felt it was distasteful for officers of the law to draw weapons on children, and used CGI to swap the guns for walkie-talkies.

Jurassic Park

Jurassic Park is known for pioneering some incredible CGI effects, many of them the result of blending techniques used in stop-motion film making with modern innovations in computer graphic design. But the dinosaurs weren’t the only things being rendered that way.

In the scene where Dr. Grant, Dr. Sattler, and John Hammond’s grandchildren are forced to escape into the air ducts of the Visitor’s Center, Lex nearly plunges to her doom. The moment where she nearly falls from the edge of the duct to the hungry velociraptor below featured a stunt girl that inadvertently looked into the camera. CGI had to be used to put the actress’s face over hers rather than reshoot the scene.

War For The Planet Of The Apes

While audiences know that the talking bipedal apes featured in the new Planet of the Apes trilogy aren’t real (and also not all played by Andy Serkis), they may not know how CGI is utilized in the rest of the films. Some of the most impressive uses of it are featured in the third film, War for the Planet of the Apes.

While CGI specialists were busy using programs to individually create strands of ape hair, they were also using them to create individual droplets of water, and leaves on trees. A great deal of the forest the apes used as their hideout area, as well as the terrain featured during the battle sequences, was entirely made of CGI despite looking incredibly life-like.

Children Of Men

Children of Men was a universally celebrated sci-fi movie when it debuted, in large part due to its visceral vision of a dystopian future. In a time when children aren’t born due to infertility reasons, one man must protect the last child of humankind and defend it from a myriad of dangers.

The last baby that Clive Owen’s character protects wasn’t a real baby at all due to the hazardous nature of the scenes it was featured in (especially him running and jumping across rooftops or amidst gunfire). Therefore it was necessary to use a CGI baby that’s so life-like it fooled audiences completely.

Indiana Jones And The Kingdom Of The Crystal Skull

While most wouldn’t classify Indiana Jones and the Kingdom of the Crystal Skull as a sci-fi film, the ending would solidly place it in that category. It features the beginning of the Atomic Age, and positions Indy in a world that’s beginning to become completely immersed in what lies among the stars.

In the opening sequence involving two hot-rods racing (a 1950 Ford Deluxe Army Staff Car vs a 1932 Ford Model B Roadster), one of them rides over a gopher hole. The little critter almost gets himself decapitated by the Model B, before scampering off. That gopher was entirely CGI…for some reason.

Waterworld

Waterworld was an ambitious project, some would say too ambitious for a sci-fi film. It was plagued by every conceivable problem on set, had an incredibly bloated budget, problems filming on oceanic locations, as well as hazardous working conditions. It also spent a hundred thousand dollars on making the ocean CGI.

Despite the fact that aerial shots exist, there are scenes in Waterworld where the ocean is CGI, and while it looks fantastic, this contrasts pretty spectacularly with shots of the real thing. This is why the budget ballooned from $100 million to $175 million.

Supernova

It’s General Hospital, in space! Or it’s Supernova, a sci-fi thriller that positions a hospital ship in deep space. Their continuing mission? To answer intergalactic 911 calls. When the Nightingale 229 answers a distress call from another ship, the survivor they bring on board and his alien artifact may trigger a supernova that will wipe out the galaxy.

Before that catastrophic event happens, there’s time for a little hanky-panky. In zero gravity, Angela Bassett and James Spader’s character have a sex scene, except they weren’t on set to do it. It’s really their co-stars, Peter Facinelli and Robin Tunney, with Tunney’s skin tone altered in post-production to match Bassett’s.

Return Of The Jedi

While some Star Wars fans found things to gripe about in the original trilogy’s third installment it was, on the whole, a fitting climax to one of the most beloved saga’s in sci-fi history.  George Lucas would later come out with a trilogy of prequels for Star Wars fans to complain about and, armed with new advancements in CGI, he would go back and alter their beloved film. If you’ve never seen any other version of the film, you may think the alterations were normal.

When Luke takes Vader’s mask off so he can see his son with his own eyes, we see that Vader has no eyebrows in the 2004 Blu-Ray edition. This is because Lucas felt they should’ve been burned off on Mustafar where he sustained the injuries that put him in the mask to begin with, so CGI was used to remove them. Too bad he didn’t stop there…