After the ship crash, Vansen counts to "3-one-thousand" from the sight of the crash to the sound reaching them and claims this equates to 10 miles away using the speed of sound on Mars. The density of atmosphere required for this to be correct is much higher than the actual one on Mars, or even Earth. The required atmospheric density would be similar to that of steel.
A lot of the Marine recruit's haircuts are way to long for military service, but it is a fictional show.
In order for communications from the first colony, 16 light years away, to reach Earth within the time frame implied, the comms would have to travel at roughly 140 times the speed of light.