A prop well is used when Hanley brings up a bucket to get some water. He pulls on a long rope and finally the bucket appears, leaking all the water from bullet holes in it. Frustrated, Hanley throws the bucket back in the well. The rope never moves to indicate the bucket is falling, a clatter is heard as the bucket hits the walls and floor of the prop well, and a couple seconds later, a splash is heard. As Hanley leaves the well, the rope has changed position by itself.
When Hanley realizes his canteen is empty, he throws it away. He should keep it in case he comes to some water. When at the well and desperate for water, he fails to try lining the bucket with his field jacket, or putting the dead German's helmet into the bucket, or even raising the bucket faster before all the water drains out.