Cage: [Being strapped into the power armour] I've never been in one of these before!
Griff: I've never been with two women at once either, but if that day ever comes, I'll make it work.
Master Sergeant Farell: Two minutes to drop, it's all right to be scared. Remember, there is no courage without fear.
Major Bill Cage: I'm not a soldier.
Rita Vrataski: Of course not. You're a weapon.
Rita Vrataski: Come find me when you wake up!
Rita Vrataski: What do we do now?
Major Bill Cage: I don't know, we've never made it this far before!
Chosen answer: First it should be noted that this film is based on the Japanese novel "All You Need is Kill" by Hiroshi Sakurazaka, which is where the term "mimics" comes from and could be something lost in translation (they adapted to alien planet environments by mimicking the biology of the planet's life, not necessarily making themselves look like a certain species). However, in the film itself it, was said the aliens "mimic our every action", militarily speaking. This is of course because the aliens were resetting the timeline when an alpha died and knew what the military would do, but to the military (and news reporters) it looked like they were just copying our fighting style.
Bishop73