If ever there was an argument for the continuation of director commentaries, it's this little nugget of information that's been revealed in Rian Johnson's commentary for The Last Jedi.
According to Johnson, in every scene where Laura Dern had to fire her blaster, she made a 'pew' noise. Example below with .gif and referencing tweet.
"You can see Laura Dern say 'pew' when she fires the gun, which she could never not do every time she shot it." — Rian Johnson, Star Wars: The Last Jedi Commentary pic.twitter.com/Wkr803BQte
— gabrielle (@daisyridleee) March 13, 2018
Of course, actors making noises isn't anything new. Antonio Banderas, when filming Once Upon A Time In Mexico, messed up a few shots because he kept making shooting noises with his mouth when he fired. Not only that, Alan Rickman apparently couldn't fire any of the guns in Die Hard with his eyes opened, no matter how hard he tried.
Harrison Ford, when he was rehearsing for A New Hope back in '77, kept making 'bang, bang, bang' noise during the spaceport shootout.
Actors - they're just like us.