Not sure if this has been brought up before but I did search briefly for anything related to what I want to bring attention to.
In the scene where Nethead impales one of the Predators with its tail, it's clear that the length of the tail is... quite long. But when it's fighting the second predator, it isn't 'quite' as long.
Are Alien's capable of extending their tails or was that just a goof?