Before I get into the actual question, I'd like to say that my only knowledge on Einstein's Theory of Relativity (both Special and General) have been obtained through about an hours worth of videos and a book about him, Einstein: His Life and Universe So please correct me if I'm wrong about the definitions, origins, etc.
So, in one of Einsteins thought experiments, he imagines two people in separate boxes, one in a gravitational field while the other is moving upwards at a constant velocity (I'm sure you probably already know this thought experiment). Anyways, Einstein states that with no reference to anything outside the box and the only information obtainable is what is happening inside the box, makes the conclusion that its pretty much impossible to figure out which one they are part of, the gravitational field, or moving upwards.
Instead of a box that moves upwards, what if it was something like a long hallway; say you shot a gun at one end to the other. Would the bullet move relative to the velocity of the box/hallway (a straight line), or would it appear to fall downwards as the box moves upwards?
PS: This is my first time using this website so sorry if it seems a bit unprofessional :P