Its synopsis noted that the episode featured the Doctor "Trapped in a world unlike any other, the Doctor faces the...". By 10 May 2020, the episode was available on BBC iPlayer along with the rest of series 9. Petronella Osgood had started watching the episode sometime before then. (WC: The Zygon Isolation)
Behind the scenes
This is a in-universe counterpart of the real world Doctor Who television story Heaven Sent that exists within the Doctor's universe. It was a visual meta-fictional cameo in The Zygon Isolation, where Petronella Osgood and her Zygon duplicate scroll through BBC iPlayer searching for something to watch.
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