20 Things You Somehow Missed In Alien

As we'll get to in a moment, the chest-burster scene isn't the only instance of the camera capturing the cast's genuine reactions to something happening in front of them. In the scene where Veronica Cartwright slaps Sigourney Weaver for not opening the airlock, all of the initial takes didn't quite look right because a) Cartwright didn't hit very hard and b) Weaver knew it was coming and pulled out a fraction.

So, on a retake, Scott instructed Cartwright to not only hit her co-star as hard as she could, but to do it fractionally earlier than she was supposed to. The result is literally and figuratively striking, with Yaphet Kotto, Harry Dean Stanton, and, obviously, Weaver herself, absolutely stunned.