Lucasfilm

BB-8 had already stolen the Internet's heart (and all of its money) long before "Star Wars: The Force Awakens" hit theaters last month, but there was one moment during the film that shocked and delighted every single person in the audience: when Finn gives the little droid a thumbs up and he responds with one of his own.

Lucasfilm

But believe it or not, that scene wasn't part of the original plan for "The Force Awakens," says special effects Neal Scanlan, who leads the "Star Wars" creature shop and was tasked with bringing BB-8 to life.

"It was never in the script," Scanlan admitted. "It was probably something that J.J. either came up with on the day, or certainly came up with later."

While there is a real BB-8 droid who exists and regularly walks the red carpet with the rest of the "Star Wars" cast, there were parts of BB-8's performance that couldn't be achieved with puppets and physical droids alone, so the crew used a combination of practical effects and digital effects to bring him to life.

"Neal built a real BB-8 and he was puppeteered through the movie, but obviously there were moments that practically we couldn’t achieve -- like him rolling around inside of the corridor of the Millennium Falcon, set moments where he was moving pretty fast across the desert, or something like that," said Roger Guyett, the visual effects supervisor at Industrial Light and Magic.

"So we built a digital version of him, too, and now in the movie you’ve got probably a quarter of the shots that are digital. Because we built the real thing, we were able to match really well to the practical version of him. And of course, [director] J.J. [Abrams] could direct him like a real character, so the most important thing was that his character was so well developed by having a real puppet."

So what about that thumbs up moment? Unfortunately, the "real" BB-8 doesn't have a lighter stowed away inside of him -- but he was certainly there on set that day, and everything but the lighter is real.

"I think the reaction that BB-8 has to Finn would have been a practical effect that we shot on the Milennium Falcon, but the reaction to the thumbs up is something that definitely came later in the day," Scanlan said.

"That thumbs up moment is exactly that," confirmed Guyett. "I think it’s a real BB-8 and then we inserted a CG panel and its arm that came out. So all of his tools, if you like, when he fires his wires and he does that stuff, that’s sort of digital CG."

It was also a lot harder to design BB-8's lighter than you'd think.

"We did several different prototype ideas of what that could look like, and we had various amounts of metal and plastic on there," added Patrick Tubach, another ILM visual effects supervisor for the film. "One of the difficult things with animating something like that is you have to be very careful that it doesn’t look like he’s giving you some other sort of gesture! We moved all the pieces around to make sure it was very clearly a thumbs up over any other kind of 'salute.'"

Although, come on, we're sure BB-8's got that tool in there somewhere as well.

While most of his interior panels were CGI-ed in after filming, the physical version of BB-8 did come with his own surprises two. one of those panels was practical -- the one into which Poe Dameron (Oscar Isaac) inserts the map to Luke Skywalker at the beginning of the film.

"That’s the great thing about collaboration," Guyett said of the juxtaposition between the digital effects and the practical ones. "You get the best of both worlds!"