This short feels like it's a condensed version of a larger story.
Sure that's kind of the point with the shorts, but Specimen managed to do everything it needed to do within 10 minutes whereas this short actually doesn't feel like its done.
I think I know what's wrong with the emotional issue here though..., the camera is in the wrong spot.
See if you can't get your actors there emotionally then you focus on the chest bursting and you can record the freakouts or dub them over later. Inter-cut that with people moving to get the medical kit, the guy freaking out and trying to save his friend, and the older guy trying to keep the victim elevated and then BOOM burster. We cut to the burster rising out of the guy and maybe to sell the guy freaking out the thing turns to the victim's friend to get him to pull the gun.
That's my half-assed way of editing that scene but as-is, the shot feels like its being shown on a stage and that doesn't work because you then need all your actors facing a certain direction and they'll essentially keep themselves contained to that area. It's basically the rule of "always face the audience" and because they aren't cutting, the actors aren't allowed to have their big moments. They have to look good at all angles and without the cut you can't see how personal it is for them, their just freaking out and can't have that emotional moment because you gotta do it all in one take.
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Also is it just me or did anybody else imagine the chestburster was riding a skateboard when it was coming towards the camera? That was way too smooth for the distance it had to cover and how quickly it did it.