Final answer:
The stage manager is the key role responsible for overseeing the running of a production post opening night, managing the transition of cast changes, and coordinating the stage crew's tasks to ensure flawless execution of each performance.
Step-by-step explanation:
The stage manager is the most important job to a production once the play has opened and is running. While the director is crucial during the rehearsal process and dress rehearsals, ensuring that the integration of design and technical elements aligns with the vision of the production, it is the stage manager who takes over to run the show upon opening night.
The stage manager is in charge of calling the show, overseeing the stage crew, and maintaining daily interaction with the actors and the producer.
Post opening, even if changes occur such as an actor needing to be replaced, the stage manager handles the transition and ensures the incoming actor is familiarized with the blocking and directorial notes.
This role is also responsible for coordinating with assistants and the stage crew, who operate stage systems, manage scenery and props, and keep the stage safe for performers.
In short, while the director makes the crucial creative decisions during the preparation and rehearsals, the execution of the performances and the oversight to ensure everything runs smoothly during the run of the show fall to the stage manager and the stage crew.