A trapdoor rejection subsystem includes one or more trapdoor rejection mechanisms. Each trapdoor rejection mechanism is configured to be selectively transitioned between a closed position to support parcels and an open position to allow parcels identified as unconveyable to pass through the trapdoor rejection mechanism. Each trapdoor rejection mechanism includes a first door, a second door, and one or more actuators which can be selectively actuated to rotate the first door and the second door and transition the trapdoor rejection mechanism between the closed position and the open position. The trapdoor rejection subsystem can be utilized in a conveyor system in combination with one or more robot singulators, an upstream conveyor, a place conveyor, and a vision and control subsystem. Detection of unconveyable parcels and the transition of each trapdoor rejection mechanism of the trapdoor rejection subsystem is controlled by the vision and control subsystem.