I loved how she was somehow coated with a sheet of ice there at the end.
What I meant about the shotguns was that:
1. The shotshells showed evidence of having already been fired, thus they wouldn't have gone off at the end of the movie.
2. The hammers that make the shotshells go off didn't have the necissary parts to them to cause the shotshells to discharge.
3. The distance between the shotshell and the hammer was great enough for the doctor to place a piece of metal between the hammers and shells, which would prevent them from combusting. The hammer would just smack into the piece of metal, and that would have been it. She could have then held the hammer, moved the piece of metal, and gently set the hammer down, disarming the collar.
4. The shotshells were only secured in place by a U shaped piece of metal, which would have allowed the doctor to remove them by hand whenever she wanted.
5. This is after the fact: The shotshells weren't secured during combustion except for the hammers that caused them to explode and the small U rings that held them down. This means that rather than channelling the shot into the doctor's head, the shells would have just exploded *around* the U rings, and also gone flying out of the collar rig. You see, Newton's law applies here. Assuming it's 000-buckshot that was in the shotgun shells, then the shot would have exited the shell at 1100 FPS. Now, when that force is projected out the front, the shotshell is compelled by Newton's law to move backwards, also at 1100 FPS. The reason the kick on a shotgun is so rough is because you're taking roughly (this is disregarding the mass of the shotgun itself) the force of the 1100 FPS into your shoulder. Now, since the shotshells int he movie were unsecured, they would not have stayed in place after discharging, they would have flown out of the collar at likely 1000 FPS, breaking the hammers. The doctor would likely have died regardless, but her injuries would be less severe, and the collar would have been ruined.
Think of it this way: when you fire a traditional firearm in space, let's say an AR with a 3600 FPS varmint load, then the bullet will exit the weapon at 3600 FPS- but you will also go backwards at 3600 FPS, because there's no force pushing back against the force of the bullet. With the collar, there was no force pushing back against the shotguns as they discharged.
But the Newton's Law is sort of a moot point, since the shotshells would have just exploded, not into her face, but around the U ring. The intention of the chamber of a gun is to contain the explosive force of what it's firing; if you just detonate any bullet without a chamber around it, the round will explode in all directions.. since there's nothing to contain the explosion.
At the end of the film, the shotshells are shown held naturally in place, which is the last thing that would have happened.