Immediately after he is shot by the poacher, a hole can be seen in Scarman's jacket. When he turns away from the window after ordering his minions to kill the poacher, the hole is gone.
Just before Scarman is shot by the poacher, as he approaches the priest hole, the square outline of the metal plate (to protect the actor from the explosive squib) can be seen underneath his jacket.
It is made clear that Horus and the other Osirans imprisoned Sutekh on Earth (in the pyramids in Egypt) seven thousand years earlier. Even though his imprisonment was supposedly safeguarded by the "Eye of Horus", an ancient power source located on Mars, surely it would have been more prudent to secure Sutekh on a planet without a population where he was less likely to be discovered and set free.
Sutekh is imprisoned in a pyramid in Egypt by a forcefield which is powered by radio signal from the Eye of Horus on Mars. However, Mars and Earth are not always in direct line of sight to each other during their orbits (Mars completes an orbit of the Sun every 687 days, compared to Earth's 365 days). Therefore, there will be times when the Sun is between them which would block any radio signal between the two planets for months at a time. In fact, even the Earth and Mars spinning on their own axes would break the radio signal.