I'm trying to work on an A/P/AvP video project in my spare time and was going through ALIEN with a fine-tooth comb.
Love it.
Also your useless trivia for the day: The Alien is on-screen - like, literally visible on screen - for all of 3 minutes 45 seconds and 19 frames (at 25fps). And that's including shots where you can see light on its dome in the vents, or one or two frames where it's visible in the background as Ripley runs into the closet on the shuttle, or shots where just parts of its body are in frame.