The Boiling point of methane is -263.2°F The coldest recorded temperature on Earth is -135°F A flowing river of methane is physically impossible on this planet.
Based on the rank clearly visible on her chest, Carolyn Hales is a Private First Class (a junior enlisted soldier), however Colonel Hughes incorrectly calls her Lieutenant (a junior commissioned officer) throughout the film. A Lieutenant would have either a black or gold single vertical bar on their chest.
"We need a high-velocity detonation to obliterate the methane pool". "Petroleum explosives have a higher detonation velocity than chemical". Petro boombas - 1800m/s, C4 - 26.4km/s, Octanitrocubane - almost 2x that of C4. C4 is almost 15x more powerful than a petrol boomba. Even TNT has a higher detonation rate than any petrol boomba at 6400m/s.