Continuity mistake: When the MR-1 first lands on Mars, the sky visible through the portholes is fiery red, which is the uniform color of all exterior shots in the film. However, a whole series of interior shots throughout the film show that the sky visible through the portholes is suddenly and inexplicably baby blue. At two points, when Iris sees a Martian through the porthole, the sky momentarily turns pitch black.
Deliberate mistake: For all exterior shots on the surface of Mars, the crew's "pressurized" space helmets have no face-plates (their faces are fully exposed to the hostile Martian environment). The transparent face-plates they intended to use reflected far too much studio set lighting, such that the glare would have obscured the actors' faces. On a $200,000 budget and a 10-day production deadline, they simply scrapped the face-plates and shot the scenes with wide-open helmets.