The room presents the characters with a center room which is occupied by a spike-filled pit. The only way around the pit appears to be walkways to either side of the spikes.
The visible pit is an illusion, as is the section of the roof above the walkways. In Reality, the roof is covered with rows of spikes not unlike those in the pit.
So, walking across the “pit” is actually the safe way through. Using the walkways causes the springs beneath the floor to slam those sections against the ceiling. Ouch.