At 1hr 26min and 01 to 02 seconds, when the alien that was being operated on attacks the scientist attempting to open up the door, you'll notice that there is a hand shaking the dreads that are coming out of the back of the alien.... nice ring too

It is over very quickly so you will need to move frame-by-frame in order to see all of the slip-up, but you should notice it with a good keen eye.