I don't usually watch it but have been for the tram crash drama, see more of the cast in real life than on screen as I work near where they film it.
They were saying they had prerecorded a version "in case" something went wrong but were still intending to do it live, were saying in the local news they had taken precautions against people trying to disrubt the live filming but not sure what as it's right in the city centre so goodness knows.
I saw the phone in story too, crazy! Some nutter also made some prank call about it too, kept the emergency services on for 5 minutes "reporting" it!