Being on the Star Trek set while The Doomsday Machine was being filmed meant that writer Norman Spinrad could give useful advice when egos got in the way of a good story.
Spinrad was there for all of the filming, which was not common. “That was very rare,” he said. “They usually don’t allow writers on the set. I was twenty-seven years old at the time. It was the first thing I had done. I’d done what he’d asked me to do, in terms of writing the episode to budget, and so I guess he trusted me to be there.”