Cool! How would navigation actually work? Dead reckoning? Inertial? Stellar reference? Pulsar navigation? Also, the dashed red line is --- SPOILER ALERT

Cool! How would navigation actually work? Dead reckoning? Inertial? Stellar reference? Pulsar navigation? Also, the dashed red line is --- SPOILER ALERT! ---- only part of the trajectory in the film, as there is another leg of the voyage not shown.