An extraterrestrial interstellar spacecraft that’s shaped like…well…a saucer.
A robot minion.
A dashing, square-jawed hero who can deliver a mean round house punch to the jaw. When the woman falls and screams (with her hand covering her face, palm facing away from her), the hero will pull / carry her to safety.
The screaming-and-falling-down woman must always hurt her ankle.
Men never hurt their ankles.
Don’t forget being able to see the wires!
MAN-IN-SUIT!
A character (usually a scientist) who says at the end of the film, “There are some things that science cannot explain,” or similar.
rumpled, thin-gauged vinyl rubber space boots, funny textured knitted clothes (pre-spandex era.)
And a HELLUVA lot of aluminum foil used for props! ACRES of the stuff! And the internal walls of spacecraft are covered with billions of toggle switches and military formations of small light bulbs, whose only function is to blink off and on with regularity.
Blasting off means everyone sits in the special spacecraft chairs, and then the camera is tilted 90 degrees while somebody jiggles the floor.
~VOW
double that if the use ‘you may not know this young lady, but…’
Oh, and at some point, someone has to be told about the monster, only to respond with some variation of “What is this, some kind of a gag or something?”
Thank you! Now it makes sense!
In fact, I believe the suits forced the director of “Day The Earth Stood Still” to film and insert the bit where Klaatu tells Helen that his resurrection is temporary or not quite what it seems, because the power over life and death is “reserved to the almighty spirit.”
Or they forced him to add it to the script. Or something.
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I liked it.
And she never just sees “it” and screams. She always stares, her face filling with terror which builds up, and finally she screams. Like a sneeze.
Seems to me that most people spotting an “it” instantly jump backwards and go AGH! in a nanosecond.
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The soundtrack has to have a Theramin playing.
Pointy tits. Gotta have pointy tits.
Cool! Thanks for the links.
Oh. SP was way ahead of me with it.
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Don’t try this at home!
No, wait…I did that frequently. 
Sorry to resurrect this zombie, but last night Mrs. R and I watched Back to the Future for the first time in a considerable while. I was pleased to see that even though it was made in the Eighties, it still has a number of the Essential Features:
Helicopter
Science lecture
Screaming woman
3/5; not bad! 
Helicopter?
Briefly, at the end, when the terrorists are apprehended.