I saw the movie and my Kerbal bell rang when the Hermes, at the fastest point in its trajectory, slingshoting around Earth back to Mars, rendezvous with the supplies probe.
Well, everywhere I read says that the movie/book is supposed to have its orbital mechanics right, and that someone actually wrote a program to verify the stuff and such. If so, how did the just launched supply probe from Earth's atmosphere, with only a few minutes of acceleration, matches the speed (within a few m/s) of Hermes accelerating for months?
Am I missing something here? Did Hermes decelerate? If so, what was the point of the slingshot? Did the rendezvous take place enroute between Earth-Mars, so that the probe had time to accelerate (and could make it there by itself)? If so, why did Hermes have to return?