The leader of the heavy equipment detail is addressed as 'major'. perhaps it was missed in the colorization, but a major would be wearing gold oak leaves collar rank insignia rather than the silver as they appear. silver oak leaves would make him a lieutenant colonel.
Near the end of the opening credits, in the close-up of the Earth, the stars behind it are visible right through the planet.
The shiny surface of the glowing alien spacecraft clearly reflects the additional lights being used to light it.
22 minutes in, outside the wooden lodge, when Sgt Gray hears footsteps in the dark, the shadow of the boom is visible as it moves across the rocks as he enters the lodge.