After they entered, the convoy personnel did not completely seal off the transition carriage; instead, they used a prop to create a transparent water wall between the two compartments.
The thin layer of water forming the water wall not only had defensive capabilities, but it could also automatically dismantle any defense walls the players attempted to erect within the carriage, ultimately forcing them to abandon the idea of blocking the line of sight and only seal off the remaining sides of the carriage.
On the side of the second carriage, there was still a metal wall, but the scroll in the first carriage had been replaced with a huge wooden box. It was unclear what kind of device was on the outside, but inside there was a large wheel. As Buzz Cut pushed it, the sound of mechanical movements "clicking" could be heard from the outside—at the same time, the wave of aliens had also charged onto the carriage!