In Serenity (2005), the Reavers and Alliance battle while Wash pilots the transport spaceship Serenity through the crossfire. In the ship, Malcolm commands his crew to strap themselves in:
Wash: We're fried. I got no control.
Malcolm: Where's the backup? Where's the backup?
Then, Jayne goes to the crew who strapped themselves in:
Jayne: Check! Check!
Suddenly scene changes to Serenity in free fall.
What exactly is Jayne doing here?