For a deep dive into how the episode was expanded for TV, the Poirot Project review details several major changes:
Some reviewers from Styles of Dying critique the episode for its "clichéd denouement" and the logistical improbability of the heist's timing (requiring the theft to occur in just a few seconds). Plot & Mystery Breakdown [S5E8] Jewel Robbery at the Grand Metropolitan
In the original story, Mr. Opalsen is an oil mogul; the TV version changes him to a theater producer to add suspects and drama. For a deep dive into how the episode