Before the impact, there is a live exchange between the astronauts and Megan Halliwell at ground control. However, there should have been eight minutes of delay between question and response.
All the exterior shots of the spaceship show the sun behind it. Going from Mars to Earth, the sun would be in front of you.
The sound of the warning buzzer (about 8 minutes) sounds as if it is in a very large building and not the confined area in the space capsule.