It was an improvised scene the audience didn't see, but Jeremy Strong freaked out the "Succession" creator with his performance in the series finale.

The creator, Jesse Armstrong, appeared on a recent episode of NPR's "Fresh Air" and was asked about Strong climbing over the railing at the river as if he may jump in during the improvised final scene of the Emmy-winning HBO series. (HBO, like CNN, is a unit of Warner Bros. Discovery.)

"I was terrified. I was terrified that he might fall in and be injured," Armstrong said. "He didn't look like he was going to jump in. But once he climbed over that barrier — when you film, there are generally a lot of health and safety assessments made, and that was not our plan that day."

Armstrong added that "normally I know that if we'd even been thinking of that happening, we would have had boats and frogmen and all kinds of safety measures, which we didn't have."

"So my first thought was for his physical safety as a human being, not anything about the character," he said. "That's what I felt on the day. Good Lord, above."

Strong, who played Kendall Roy on the hit drama, talked to CNN's Anderson Cooper about improvising the scene in which his character grapples with not gaining control of his family's media empire.

"I did try and go in the water," Strong said. "One of the incredible things about working on something for seven years... is your instincts for the thing become a part of you and are very alive. Your job is to give the writing heart and a nerve and . . . all that stuff."

Strong said he "didn't feel like (Kendall) could come back from what happens to him."