Continuity mistake: The amount of blood on Alison's padlock in the first of the group traps changes instantly. (00:22:00)
Continuity mistake: In the beginning of the movie, Strahm reaches out into the hall to grab the tape player. The string it is hanging from comes with it. Strahm exits the room, and we get a reverse angle and the string that held the tape player is hanging from the ceiling, but empty. The string should not be there to begin with.
Continuity mistake: When Ashley is decapitated, a pool of blood appears under her severed head. Later when we see the head from the second room, the pool of blood is not present. (00:26:50 - 00:33:30)
Continuity mistake: When entering the second room, the position of the door, before it gets closed, changes depending on the camera angle. (00:33:15)
Answer: That was the entire point of the trap. Each trap in the overall game was meant for them to all work together. The tape for this trap asks "Who will be the odd man out?" They took this to mean that one person had to remain outside the chambers, but what it really meant was two people would each share a chamber (assuming all five survived the first trap) and one person would occupy the third chamber all by themselves. Charles realised this and tried to tell everyone, but was unfortunately killed by the explosion before he could.
Phaneron ★
Nope actually he said who of you 4 has to die...how he knew was 4 survivors?
He does not say that at all. The exact wording is "With only three points of safety, which of you will be the odd man out?" At no point does the tape say that one of them has to die. That would be completely contradictory to the point that the five of them were supposed to work together to safely get through every trap.
Phaneron ★
Not what he meant. He knows human nature is survival at the expense of someone else. He set the trap so all could survive, but he knows the panic and self-preservation will lead the group to sacrifice someone.
The_Iceman