The dialogue in action scenes doesn’t consist entirely of people yelling each other’s names, or saying “Come on!” or “This way!”
Pointless dialogue is the number one sign of a blockbuster in crisis. And by pointless, I mean people speaking because no one’s said anything for a while, and a movie needs dialogue, right? Or yelling to draw attention to things, or clunkily convey or reinforce information.
Bad action dialogue can spring from a failure in the visual storytelling – or at least, a failure to trust visual storytelling to do the job. Someone forgot to show us a sign saying control room, or a trinket on the desk that would tell us this is the villain’s lair, so someone has to blurt “This must be the control room”. Someone didn’t trust the audience to remember that the heroine always wears purple and therefore this must be her jacket, so someone has to remember that aloud on our behalf.
It can also spring from a lack of personal goals for the characters. As we noted before, you get better scenes when your characters are strong individuals. And if they’re strong individuals, they’ll all have different goals and motivations, which they’ll have to argue for as the situation develops.
Think about the scenes on the Death Star in the second act of Star Wars. Luke wants to rescue the princess, as does R2D2. Han Solo wants to get his precious ship the hell out of here. C3PO just wants to survive. Obi-Wan is well aware of the coming confrontation with Vader. They all work together to survive, but the things they say to each other are driven by their differing motivations and their desire to get what they want or do what they have to do.
So trust the visuals, and give your characters their own angles to work, and your dialogue will immediately improve…