'The Wild Robot' director reveals he had 2 different endings for the movie

• Chris Sanders' "The Wild Robot" stays true to Peter Brown's book ending.
• Sanders faced challenges but received DreamWorks Animation's full support for the book's ending.
• The movie's ending is more cinematic, with a major battle and hints at a sequel.

"The Wild Robot" is based on a popular book series written by Peter Brown. It follows a robot named Roz (voiced by Lupita Nyong'o) who, after ending up on an island inhabited by wildlife, learns their ways and becomes a motherly figure to a young gosling.

The movie's writer-director, Chris Sanders ("Lilo & Stitch," "How to Train Your Dragon"), stayed true to Brown's ending of the first book. However, Sanders admits it was the harder ending to do, and at first, he didn't know if he was cut out to pull it off.

"I had concerns," Sanders told Business Insider. "I didn't want to finish the story with a presumption that we would make more 'The Wild Robot' movies. I just felt uncomfortable with that. "

So he came up with two endings: one that was similar to Brown's book ending and teased a sequel, and another that wrapped up the whole story. He then presented both to the executives at DreamWorks Animation, the studio behind the movie.

"To their credit, they unanimously said, 'Do the other ending, do the one that's true to the book,'" Sanders recalled. "That's a tougher ending because you have got to stick the landing."

But with the full backing of the studio, Sanders went forth with the more open ending. The result is filled with emotion and the thrill of what's to come.

Warning: Spoilers ahead for "The Wild Robot" book and movie.

'The Wild Robot' movie's ending is more cinematic than the book's

In Brown's book, three combat robots known as RECOS come to the island to take Roz back to their makers. After a battle between the robots and Roz, alongside the animals on the island, Roz is just a head and torso. She decides she must return to her makers to be repaired and keep them from returning. As she flies away, she begins to plan how she can escape and return to the island.

Sanders tweaked a few things for the movie's ending and, in the process, made it more cinematic. Instead of three RECOS, it's a robot named Vontra (voiced by Stephanie Hsu) who comes to retrieve Roz in the movie. Eventually, she calls on an army of robots to retrieve Roz. This leads to a major battle between the robots and Roz with the wild animals. There's a wildfire and a moment where Roz is taken to the mothership and the gosling she raised, Brightbill (Kit Connor), must rescue her.

Like in the book, Roz realizes she must return to her makers to stop more robots from coming. She leaves with Vontra (and unlike the book, Roz has no missing limbs). Then, there's a jumpcut to Roz, among other robots, working in a greenhouse and seemingly having been reset to her factory setting. But suddenly, Brightbill appears next to her and Roz reveals that she's still herself, hinting that she's planning a way to get back to the island.

Sanders "absolutely" wants to make a sequel

Brown has written two other books in the series, "The Wild Robot Escapes" and "The Wild Robot Protects." In "Escapes," Roz is sent to work at a dairy farm but continues to plot a way to get back to Brightbill and the island.

When asked if he'd begun work on a sequel to "The Wild Robot," Sanders answered slyly, "Maybe we are." He admitted that he "absolutely" wants to make a sequel.

"In this first book, Roz is a victim of circumstance. She's lost, and it's outside her control. She's in a circumstance beyond her control," he said. "But in Peter's second book, she's working the problem, and she's more in charge of her journey." 

"The Wild Robot" is now in theaters.