It would have been really neat to see ISRU for the subsequent lift offs. In-situ resource utilization. Basically you land a solar powered robotic rocket fuel

It would have been really neat to see ISRU for the subsequent lift offs. In-situ resource utilization. Basically you land a solar powered robotic rocket fuel factory that converts water ice and CO2 into methane and oxygen using electrolysis and the Sabatier process. Then, when your rocket lands, you refuel for takeoff. Still plenty of opportunity for drama, and not a whole lot higher CG budget. Of course, that only fixes the first bit of magic. It doesn't fix the other issues or the many other problems with the movie, like all of Matt Damon's dialog.