The unmasking of Kylo Ren in Star Wars: The Force Awakens is a key character moment. That Kylo is not, in fact, yet another scarred evildoer but a testy, vulnerable bad guy clinging to dreams of becoming his grandfather helps explain much of what he does in the rest of the movie. And it almost happened way earlier in the movie.
On the commentary track for the 3D rerelease of The Force Awakens, J.J. Abrams talks about the realization, in post-production, that unmasking would have far more impact later in the movie. Unfortunately, they’d already shot a crucial scene, where Ren speaks to Supreme Leader Snoke, with the mask off. So instead of going back and reshooting it at enormous expense, the effects team created a CGI version of the mask and layered it over Adam Driver’s face since they were working on the scene anyway.
It’s a subtle bit of CGI that completely changes the movie, building up the suspense of just what’s under the mask. And it’s also completely unnoticeable. Well, until now, since Abrams has pointed it out. It’s probably all you’re going to see when you watch that scene. Quick, let’s speculate about who Snoke is instead!