Weightlessness appears to affect some props (harmonica, jacket), but not others (sandwich, papers, long hair, ties).
During the course of the movie, the fuel gauges for the rocket always remain at "empty".
As the rocket descends to the Martian surface, Harry continually reports their altitude. Their rate of descent increases until, from 15,000 feet to 6000, Harry is calling out the loss of altitude at the rate of 1000-2000 feet per second. At 6000 feet, Eckstrom says, "We're losing altitude too fast. Increase thrust to 3000 tons," whereupon Floyd slowly shifts the controls to increase the thrust. Between the time Ekstrom starts talking and the moment the rockets are heard starting their heavier thrust, at least 7 seconds elapse - which, according to the accelerating rate of descent previously called out by Harry, would mean that the ship should have crashed before Ekstrom finished his sentence.
When the two crewmen head down to work on the engines the bridge gravity indicates they are oriented parallel to the long axis of the rocket. When they are in engine room it is are oriented perpendicular to the long axis.
During the ships descent to Mars, one of the characters said "the ships altitude was 50 miles". The next scene showed the altimeter with an altitude of 60 miles.
It is mentioned that the gravity on Mars is 1/2 of that on Earth. Martian gravity is actually 38% of that on Earth. The rocks thrown by the cavemen would not be nearly as dangerous as posed.
When the rocket reduces power the first stage of the rocket begins approaching the second stage in a violation of the laws of physics. The rocket has pulled away from the first stage and even if the power of the second stage was completely cut off inertia would keep the second stage moving faster than the first stage.
Mars is roughly 35 million miles from Earth, while the Moon is roughly 240,000 miles from Earth. Even if the X-M was carrying twice the needed fuel supply, it is highly unlikely that they would be able to reach Mars and return to Earth.
at 20 minutes the question is asked; "say what happened to the rest of the night" and answered with "I'm afraid we ran right out of it. If it's perpetual darkness you want wait until we reach outer space...the realm of perpetual night"
Except that unless one stays in Earths shadow, it is PERPETUAL LIGHT, especially if you're still on a lunar insertion flight path as they were until minutes later in the movie...
On way to the Moon the RX-M encounters a cluster of asteroids. Lloyd Bridges character yells out "meteorites"! To be a meteorite, a meteor (Shooting Star) must survive traveling through the atmosphere and hit the ground.
One of the earth models seen through the porthole of the ship appears to have a visible seam.
As the rocket descends through the Martian atmosphere, the clouds visible through the portholes are sideways.
When the rocket ship is launched for the first time, most of it is transparent, allowing the launch pad and other background props to shine right through it.
When the rocket lands on Mars, we see a shot of German V2 rocket-in reverse. We even get a quick look at the rocket tower as the rocket goes down.
The mission is supposed to be a trip to the Moon. Yet the crew is well supplied with firearms -- of no use on a lunar expedition.
While the added tinting to make Mars the "Red Planet" of lore makes for an an interesting effect, it also creates a kind of "logic loop". This tinting should also not only be visible when viewing the planet through the portholes, but it would cast this same tint through them, lighting the much of the interior of the ship's cabin red during the landing and while on the planet. But if that were the case, the areas of the interior NOT lit by this tint would remain in B&W, further betraying the film's own look and showcasing the gimmicky use of the tint in the first place.
It seems totally illogical that the crew would have no back-up communication system with earth, not even a powerful morse code transmitter.
If the XM has a radar system on-board then they should have had advance warning of the incoming meteor storm.