Goofs

When Trent is pursued in the alley, he crouches and moves an empty barrel to conceal himself. In the next shot, the barrel is in its original position.

At 27:45, the glass hand tells Trent that Durn has come through the time mirror. Trent immediately takes Consuelo in his glass hand and flees the room. His glove is on, covering the glass hand, yet there was no time to put it on.

Trent's glass hand is his left, and his normal hand the right. At 2:15 a close up shows him removing a chain and picking up a gun with a normal left hand, then immediately discarding the chain with a normal right hand.

The glass hand tells Trent that the future Earth has been contaminated with a radioactive substance that has a 99-year half-life, and that the radiation will dissipate within 200 years. This is a complete misunderstanding of the nature of radioactive decay. Half of a radioactive substance will decay in the time period called a half-life. When another half-life passes, half of the remaining substance will decay, and so on. It would take many millennia for a substance with a 99-year half-life to decay to the point of being virtually radiation-free.

Opening narration by the Control Voice lists several ancient civilizations, including one described as "Sumerican." There is no civilization so named; presumably the ancient Sumerian civilization was the one intended.

The opening narration cites a legend of Gilgamesh, an immortal man who appears at different points in history; however, the Gilgamesh legends in known classical literature make no such claim. The only story arc of Gilgamesh relating to immortality is that he sought a plant that would make its eater immortal, only to have the plant stolen from him at the last minute by a snake.

During the cold opening, the narrator lists off a series of ancient civilizations. When he gets to the Sumerians he pronounces it "Sumericans". There was no such place or civilization. Obviously the producers didn't think that audiences would notice the mistake, however the screenplay was written by Harlan Ellison who would've had a fit when he heard the first broadcast of his story.

The humans released radiation to kill the Kybans, but the Kyban who comes through the mirror says there is some king of unknown bacterial plague killing them. Radiation is not a form of bacteria.

When Trent's glass hand has only one or two fingers, he is seen using all fingers when gloved. This is most obvious when he holds his left hand over Consuelo's mouth to keep her silent and when he retrieves and grips the second finger with his gloved hand.

The glass hand is stiff and the fingers immovable, yet Trent uses the hand to grasp objects on several occasions.

When Trent removes his glove to add the third finger, he can be seen twisting to loosen a finger already inside the glove next to the index finger. This came off with the glove. He then put the third finger in its place.

When Trent knocks out the first Kyban the seam in the stocking pulled over his head that is supposedly his skin can be seen.

When a Kyben was shot at 10:10 and slumped over a railing, what actually fell over the rail to the floor below was clearly a limp, stuffed dummy instead.

It is odd that an alien race, so advanced that they travel through time and space, are using revolvers as weapons.

Just before he rips the medallion off the Kyban, he asks him what it is like when they are sent up. Since the process kills them, it is an impossible question to answer which makes no sense asking. It's like asking a person what it is like to die, no living person can answer that.

The Kyban are searching for Trent to get the glass hand and discover where the humans are hiding, yet the Kyban leader tells Trent that he is the last human left, implying they have all died. If all humans are dead then there is no reason to look for the glass hand to find them.

Trent has a gun which he uses to kill some of the Kybans, but he lets one of them rush him without shooting thus allowing the Kyban carrying the finger to escape. Something no sane person who is fighting for his life would do, although it makes for more excitement and is a time filler.