You are technically correct. However, there is a possible way it would work. If the lid was a clear color, with a dark, solid colored center. Then you would see a ring of light if a light were shining above at the time you looked up the well.
For the record, I have never seen or heard of this movie, so I have no idea of what it is about.
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If a man does not keep pace with his companions, perhaps it is because he hears a different drummer.
Let him step to the music which he hears, however measured, or far away.--Henry David Thoreau