Continuity mistake: When Jake and Grace are tied up for execution, Jake is on the left and Grace on the right (from the audience's POV). When Mo'at cuts them free, Grace is on the left and Jake is on the right.
Suggested correction: Jake and Grace are tied by their hands to an overhead beam, which allows for 360° of bodily rotation. When the gunships arrive Jake and Grace are facing them, with Jake to the right and Grace to the left, as we see them on the screen, looking at their front. Shortly after the gunships open fire, we see Neytiri turn away from the gunships and run past Jake and Grace. We see Jake turn 180° to call to Neytiri. When Mo'at approaches Jake and Grace we can see the gunships behind both Jake and Grace. As such both have turned 180° and Jake is now seen on the left with Grace seen on the right.