The craziest thing about the "Alien" franchise is just how much of its success seems to have come about at least partially by accident, or by improvisation. By the second movie, Sigourney Weaver's Ellen Ripley had been firmly established as the face of the franchise, as well as one of the most beloved sci-fi leads of all time, but in the original script for "Alien" her character wasn't even supposed to be a woman. Even after Ripley's gender was flipped, the decision to let her survive had little to do with feminism or making Ripley into a franchise lead, but just with subverting expectations. "No one on that film was a feminist," Sigourney Weaver said in a 2006 interview. "Everyone thought, 'Who will ever think the woman is gonna be the survivor?' So it was just one big gag."

There's a common fun fact thrown around about "Alien...