This was an interesting read, and the scene with the actual interrogation is really cool. However, it's very clear that this screenplay still needs a lot of TLC.
My first problem with this script is that you only barely described the setting. You do hint at a setting, which is good, but you have to remember that a script is not meant to be read for its literary genius. It's meant primarily as a way for directors, DPs, and actors to get the information they need about the story before and during filming. When you write a screenplay like a novel, it often ends up making everyone else's jobs harder--meaning no one will want to buy your script.
Something that you must always keep in mind is, when a scene ends with a character leaving a room, you typically should use the verb 'exists' (e.g. He opens the door to his right and exits; Morgan exists through the door; etc).
It's also really important that you don't leave important story elements in the action. The action should only be reserved for action and description.
Morgan's commander, a cold looking man,
JOHN (50's), talks to a few surveillance
workers, then walks over to greet Morgan.
I understand the urge to write that John is Morgan's commander, but this information has to be given some other way. Perhaps Morgan salutes John and John says "at ease, soldier" or John is wearing some sort of emblem that makes it clear that he ranks higher than Morgan. The viewer of the movie will not be reading the script, so it's important to stop yourself doing that early on.
They walk toward a screen monitor.
JOHN (CONT'D)
You're the best negotiator
we've ever had.
They approach the monitor and MORGAN sees a
weird, skinny arm twitch on the screen.
It's redundant to say they walked toward a monitor and then approached it. Redundancies up your word count and make your screenplay seem amateurish, but they're easy to cut out.
JOHN
Aliens... But we call
them Ellipticans due to
the shape of their heads.
This line feels a little contrived. It might be better to just cut out the "due to the shape of their heads" part and let the audience guess that that's what the name means.
Morgans eyes dart as he considers this.
It's okay to say "Morgans eyes dart back and forth", but "as he considers this" is redundant. The action and dialogue together already imply that his eyes are darting as a result of what he's just been told. The director, DP, and actors will know what you mean, so "as he considers this" and anything like that should always be cut from your screenplay.
JOHN (CONT'D)
No one has attempted to
do this. So get your ass
in there and get it done.
This is way too on the nose. Try reworking the dialogue to give the audience more to think about rather than just throwing all the information at them and telling them to absorb it. Instead of outright saying that no one has attempted it, you could have John say something that merely implies it. This would be more interesting dialogue, too, because it could add tension if done right.
He nods to John. A nod that says: "Yes, sir."
Another redundancy. It's very obvious that a nod means yes, so you can cut the entire second sentence.
You then go on to blend two scenes together, which makes sense why you would think to write it that way, but it's still important that in the beginning of each scene in a new location (including a new room) you have to write what the camera will see. If Morgan enters a room holding papers, you have to start with that.
He lays the paper that John gave him on the
metal table, then sits down across from the
ELLIPTICANS.
The two aliens, with small slinder bodies,
oval-shaped heads, no mouths and vast grey
eyes, sit in restraints.
It would be better if you wrote how many Ellipticans he sat across from as he's sitting down rather than in the next paragraph. Economical writing is very important in screenwriting.
Morgan gazes at them. Not intimidated.
How is he not intimidated? How will the camera see his lack of intimidation? It's not good enough to simply say he was not intimidated, especially since simply 'gazing' at the aliens doesn't really convey anything.
Morgan hears a trembling noise as their eye
color change from grey, to a deep bright
purple.
He yells at the top of his lungs in agony.
Then SLAMS his hands against the sides
of the table while tears stream down his
face.
He then becomes calm, starts to speak,
but it's not really him talking. It's the aliens
talking through him.
Again, this is too much like prose, as another critique stated. It's very interesting prose and makes me actually interested in the story, but you have to find a way to write it as action.
The Ellipticans made a trembling sound as their irises shifted from gray to a deep purple.
Morgan screams and writhes in his chair, grabbing his face as tears poor from his eyes...Something more like that is more fitting for a screenplay. Also remember not to filter the actions of other characters through the main character. So don't write that Morgan sees, hears, or feels something. Show us what he's seeing, hearing, or feeling.
Also, you should never end a scene with a line of dialogue. If you must have someone speak just before the cut, end the scene with the action "On Morgan." This conveys that the audience should be focused on whatever he just said and his reaction is important.
Overall, this is an interesting idea. It could even be a good screenplay if you finish the first draft, learn a ton about screenwriting, and then go back and rewrite everything with fresh eyes.
I hope what I said helps. Your screenplay doesn't suck, you just need to learn more about writing before it can become the polished and pretty finished manuscript that the other critics here were expecting, I guess.