Continuity mistake: When Joe goes to punch the TV screen, it shows moving lines and static. But in the shot where his fist goes through the screen, it's easy to see that the screen has been replaced with one on which wavy lines have simply been painted, and then backlit. The lines are still visible on the shards of glass after the screen is broken.
Other mistake: When Martin Landau throws the mini tape player to the floor, you hear the fast forward chipmunk sound but the reels are still spinning at the same speed as before.
Stopover in a Quiet Town - S5-E30
Continuity mistake: Bob's cigarette sets the artificial grass on fire, and he rapidly stamps it out. When he finishes extinguishing the flames, the grass is scorched, but intact. He doesn't touch it again, but one shot later, the burned grass and all its ashes have vanished and a huge hole has appeared, revealing the metal mesh underneath. (00:13:50)
Stopover in a Quiet Town - S5-E30
Visible crew/equipment: When the camera pans to Rod Serling for his opening narration, you can very briefly see several crewmembers and some backstage equipment.
Stopover in a Quiet Town - S5-E30
Revealing mistake: The actors are supposed to be in a play set for the huge child, but when she reaches down and picks them up it is obvious that it was filmed in an outdoor setting in a town much bigger than what is supposed to be the play set.
Mr. Garrity and the Graves - S5-E32
Deliberate mistake: Garrity blackmails the town citizens into paying him not to resurrect their unlamented "loved ones." Amazingly, every man in the saloon just happens to have hundreds of dollars ($500 - $1200 each) in his pocket to pay up with. In 1890 money, that's roughly equivalent to a group of modern-day bar patrons all carrying ten to thirty thousand dollars around in their pockets. The scenario was apparently used in spite of its incredibility just to more quickly advance the plot.
Mr. Garrity and the Graves - S5-E32
Revealing mistake: When the town's people are waiting for Garrity's arrival at midnight, we hear an old clock informing everybody it is midnight and they all turn around to see. But look at the time on the clock - you can quite clearly see that it is actually five minutes till 6 o'clock.
The Brain Center at Whipple's - S5-E33
Continuity mistake: At the moment Chief Engineer Hanley turns off the projector, the lamps in the background come on at precisely the same moment. Mr. Whipple is standing in the middle of the room. No one else was in the room to turn the lights on.
Revealing mistake: The strings on the guitar are extremely loose. While they would make a sound, it wouldn't be anywhere near the proper sound. The guitar sound throughout the episode doesn't match up to the strokes of the guitar either.
Other mistake: As Trooper Franklin is shining his light on the side of the car showing the fingerprints, notice the front passenger's door. The key hole and the black painted rim of it is not covered by the fingerprint, or paint as it turns out to be. But regardless, it's not covered. (00:14:15)
Continuity mistake: Just before Sport and Jeb come back from their first visit with Aunt T, their parents are walking around the pool deck where it's fairly dry. But when the children come back, the area where they are helped out of the pool is suddenly very wet, probably from earlier takes. (00:13:40)
Deliberate mistake: Sport's voice is noticeably dubbed by a different actor in several scenes throughout the episode. Her voice inside Aunt T's house is the original audio track done by the child actor. During the other scenes, the voice is done by June Foray (uncredited).
Continuity mistake: When Sport and Jab jump into the pool for last time, Sport is seen wearing a shirt. But,when she comes out at Aunt T's house she is wearing a swimsuit.
Answer: It's explained in the episode. The aliens are experimenting to see how humans react to various scenarios. This just happens to involve them using super strength.
Thanks. It's been a long time since I saw the episode so I forgot.