Firearms are wonderful and the explorers could probably rule this world if they so desired. Unless gorillas had evolved and had rifles, but then John Carradine would be awesomely amusing as a museum exhibit. Bryce wearing a mailman uniform would be good stuff too. Few films can inspire the open mouthed stare on my part, but this is one of them. Add to that a caveman flick from the Philippines and mission control on Earth having a stately view of the moon for some reason.
Vampires are from outer space.
Always wear your seatbelt when traveling at escape velocity. Solar flares can happen in deep space. Having someone place a model spaceship on a pile of rocks is hardly realism. Cavewomen shave their pits and legs. Red radiation is the most dangerous.