6. Human Cloning - Alien: Resurrection
It's pretty surprising that a sci-fi film written by Joss Whedon of all people tried to sneak something so utterly ridiculous by us, and if the notion of the deceased Ripley (Sigourney Weaver) being cloned in order to facilitate this sequel wasn't enough, The Avengers director had plenty more up his sleeve to strain credulity. After Ripley dies at the end of Alien 3, some of her entrails were swabbed off the side of the furnace from when she was chest-bursted as she fell into the fire, and this was used to clone Ripley. So far, so good, right? Well, it later transpires that this clone has memories of Ripley's prior existence, which makes absolutely zero scientific sense given that we know our memories are in no way bound to our DNA. Besides, wouldn't it cause a clone plenty of mental anguish if they remember that brief moment of pain as the fiery lava consumed their previous body? Just sayin'.