Having been attacked by a mysterious alien lifeform on a distant planet, Officer Kane (played by John Hurt) joins the rest of the crew of the Nostromo spacecraft for breakfast the next morning, seemingly unaffected by the entire experience. Moments later, a monstrous embryonic creature bursts out of his chest, killing him instantly—and kick-starting the entire Alien film franchise, way back in 1979.
It’s a terrifying scene, but it was arguably even more shocking for Hurt’s fellow Alien cast members, including Sigourney Weaver, Ian Holm, and Tom Skerrit.
Ahead of the scene, all that the cast knew from the script was that a creature would burst out of Kane’s body, and in preparation, they had been shown the alien puppet they would be confronted with. Other than that, besides Hurt himself, the cast was left entirely in the dark.
The scene was shot just once, ensuring that the reactions of the cast were completely genuine. They had no idea how the effect would be achieved—and so were unaware that the puppet had been hidden inside a replica torso filled with flesh, exploding squibs of red gel, and hydraulic syringes ready to spray them with fake blood.
The cast’s shock you see on screen, ultimately, is their genuine response to the horror.