Near the beginning when Judy calls "Mom" to the radar screen Maureen is carrying a broom or mop, yet when she gets to the control panel she has nothing in her hand. This is not just a TV cut for time as the same goof can be seen in the DVD.
The pistol the dog takes is a different color than the other pistols. The others are smooth and dark gray with a red muzzle; this one is black with a very rough texture.
At around the 25 minute mark the beast is seen looking in the window of the lower deck of the ship. This shouldn't be possible as the lower deck of the ship is below ground level.
During the final monster attack (around 48 minutes) John is firing at the monster but a laser beam effect was not added. You can see the light on the barrel of the pistol illuminate several times.
The radioactivity sensor used at around 49 minutes is just an Astatic 335 or 337 audio microphone. The same type is used on the radio communications set on the Jupiter 2, and occasionally the Astatic brand name is visible on the side of the microphone case.
Late in the story, the usually sensible Judy leaves the safety of the Jupiter 2 and, alone and unarmed, searches for the missing dog despite ample evidence of a dangerous creature in the vicinity.
Just before Maureen and Judy find the small dog it rolls down a boulder which looks to be about 50 to 100 lbs. A dog only 10 pounds or so could not possible have the strength to dislodge a rock that size.
When Dr.Smith,Will and the Robot are taking their oath to each other the camera moves in to show their hands on top of each other.The shadow of the boom mic can be seen on the front of Dr. Smith.