Continuity mistake: When Marco is in the library searching the internet for information about the scientist, he isn't wearing headphones. Then he notices the security camera recording him, and in the next shot, from the camera's POV, he's wearing them. When it cuts back to 'our' regular view they're gone again immediately, and he puts them on to listen to the computer.
Continuity mistake: In the scene when Liev Schrieber is with his mother before they go out to the party, she kisses him, than starts to lean forward to kiss him again. But when the camera cuts to the reverse angle, she hasn't moved an inch. It's as if she lunges back to her original position.
Chosen answer: Perhaps the piece-of-plastic killing was a "test run" by the brainwashers to see if Raymond would actually react to their commands. You can see other soldiers lying down wearing "halos", hinting that this happened at a different time and place than the observation room choking.