Continuity mistake: Will walks through the crowd at the hanging and stands in front of the scaffolding looking at Jack, as the official reads the list of Jack's crimes. The rope wound around the beam is wound differently here than in the close-up shots. The rope that leads up to the noose is in front of the beam. In the next semi close-up of Jack, when he smiles at the hangman, the rope that leads to the noose is now on the opposite side of the beam.
Picture added by Super Grover
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