Visible crew/equipment: When the police cars arrive after Strahm's cube trap, there is a very quick shot of the black police car passing before the camera. When it does, a white screen and black stage light are reflected on its surface. This is just before it shows the SWAT going in. (00:10:45)
Visible crew/equipment: When Jill Tuck is talking to Agent Erikson in his office, there is a shot with a boom arm's shadow visible across a picture and bit of wall, behind Agent Erikson. (01:03:40)
Visible crew/equipment: In the crushing room at the end of the film, Strahm is trying to open the box where Hoffman is. As it's descending into the ground, on the side of the box you can see the feet of a crew member with white sneakers moving around. It is not Strahm's feet: he's wearing black boots. No slow-mo is required.
Visible crew/equipment: When Strahm goes to get his gun in the crushing room at the end of the film, a boom mic is reflected on his jacket.
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