The door at the end of the tunnel is unlocked by the Butler, leading through into the cavern beyond, in Fall Out, has an electronic sign on the opposite side which says WELL
COME. That doesn't mean the Prisoner, Butler, and Supervisor are being welcomed into the cavern, just the opposite, that anyone entering the Village via that door are being welcomed into the Village! This suggests another way arrival might arrive in the Village. Other than that, the way by which the milk, the potatoes, the ice cream, and aspirins arrive at night, when most everyone else is a sleep!