Once Sonic runs into the arena, he will find an indestructible booth separating him and Robotnik. Here, the booth is colored blue in the bad future timeline while in the good future timeline, it is colored purple.
A conveyor belt will activate while spikes lower from the left side of the screen to block the entrance. The only solution is to run along the conveyor belt while the doctor moves a crane and drops small mines, which detonate into four small mines that don't travel very far at all. The machine, however, is a self-destructing mechanism, and the booth that contains Robotnik will lower against the conveyor belt after a period of time, beginning to destruct. Eventually, the machine will explode and the player is granted access to the end of the zone.