IT: Welcome To Derry Boss Says The Finale's Best Moment Wasn't Scripted

The following post contains spoilers for the "IT: Welcome to Derry" finale.

"IT: Welcome to Derry" saved one of its very best moments for last — and it almost didn't happen at all.

During the HBO prequel's freshman finale, the Losers Club — Marge (Matilda Lawler), Lilly (Clara Stack), Will (Blake Cameron James), and Ronnie (Amanda Christine) — got an 11th-hour assist from the spirit of sweet, fallen Rich Santos (Arian S. Cartaya), who broke through from the afterlife to help his friends keep Pennywise within Derry's borders.

Rich's brief but pivotal return was already a major moment in the episode, after his untimely death in the previous installment left many a "Welcome to Derry" viewer emotionally wrecked. Making the scene even more memorable, though, was the middle finger that Rich directed at Pennywise as he ran across Derry's frozen river to support his fellow Losers — a terrific moment that was not in the finale script, per executive producer Andy Muschietti.

"We did a lot of improvisation in general, and that's one of the things we created on the day, or a couple of days before," Muschietti tells TVLine. "And I'll tell you, the [resurrection] of Richie was something I came up with probably in the last few weeks [of production]. In a world where we have someone — Dick Hallorann — who sees dead people, and in a world where we lost one of our beloved heroes, which is Richie, I thought of giving a little comfort to the audience by bringing him back."

And though Rich's flipping-the-bird moment was Muschietti's idea, not Cartaya's, Muschietti says the young actor was happy to go along with the last-minute addition.

"We see the monster crawling, and it's a very anxiety-ridden ending, and that was allowed by the presence of Rich — the Loser that was not there," he shares. "And yeah, the middle finger came as the result of improvisation at the end, and since [Arian] is a phenomenal kid and a great actor, of course he was down."

"Welcome to Derry" has yet to be formally renewed for a second season at HBO — but if Muschietti has any say in the matter, the prequel will run for three seasons at the premium cabler; get full details in our post mortem Q&A with him and sister/co-executive producer Barbara Muschietti.