Goofs

When Draper gets in and out of the pond in long shots, he's totally naked, but during the time he's actually in the water, he's wearing brown trunks.

The same footage of the Martian ships arriving, attacking, then leaving, not to mention the explosions from the laser fire on the rocks, is used repeatedly.

When Draper and Friday work their way through the canals, Friday's manacles appear and disappear between shots.

When Draper first encounters the aliens and covertly records a video of them he slowly pans the camera back and forth, when he later reviews the video the shots are completely inconsistent with that.

In space; they constantly raise and lower the helmet face shields.

When Draper brings Friday back to the cave for the first time and settles down to sleep he walks around and extinguishes the burning rocks he is using like candles buy smothering them with a can on the end of a pole, supposedly starving the flames of oxygen until they go out. This would not work if the rocks generated their own oxygen when they burn as he stated earlier.

Despite being marooned on Mars for approximately 6 months, neither men's hair, nor beards show any signs of growth. On the other hand, Draper is shown shaving at one point and no suggestion is made that Friday's alien race can grow beards.

Although the story allows Kit to breathe the limited amount of oxygen on Mars, the atmosphere there is, in fact, almost 96% carbon dioxide. He would fare almost as well drawing from an automobile tailpipe.

Oddly, the monkey doesn't need oxygen.

The water-pool cave that Kit falls into from the surface is later revealed to be a 100 or more feet high, a distance that would kill a falling man. (however, gravity on Mars is only ~40% Earth's, so the fall could be less serious)

When Draper records his first log entry, at one point he says that his supplies will get him by "for about fifteen days". His lips, however, mouth a different number and you can clearly hear that this part was dubbed in later.

(at around 52 mins) As Draper is dreaming about talking with McReady, the rectangular shadow from the camera crosses over McReady's torso.

At 15:09 you can see a tripod light illuminating the purple column from behind. This is when Draper discovers the cave that he makes into his new home on Mars.

After finding Friday, Draper records in his log that Friday appears to be a mute, and may even be deaf. Draper must not have remembered Friday watching the video he recorded earlier, with Friday reacting to the sound of the laser shots from the Martian ships.

Draper finds what's left of Mac's pod, but doesn't check for any of Mac's oxygen tanks.