Of Late I Think of Cliffordville - S4-E14
Revealing mistake: When the camera is in close up on Feathersmith, the line of the skin wig is clear.
Other mistake: When Mike first walks into the town he sees the ringing church bell then looks to his right. The camera acting as his POV pans from left to right but since he was already looking to his right then the camera would be facing the direction he just came from.
Will the Real Martian Please Stand Up - S2-E28
Revealing mistake: As the Venutian asks the Martian to play music, the edges of the fake skin around the third eye is visible.
The Mind and the Matter - S2-E27
Other mistake: In the office, Beechcroft's Mirror Image's hair is styled like his own, rather than reversed, as a reflection should be. In his bathroom, the hair in The Mirror reflection is correct.
Factual error: At the end of the episode, Major General George Harper looks out the window, puzzled. As he looks out the window, we see a palm tree in front of the building that is facing the window. Reims, France, is in northern France, where it is too cold to support that kind of tree. (00:23:00)
Continuity mistake: When Caswell walks toward the phone booth and the woman exits, she passes on his right side and walks down the sidewalk. Later in the scene Caswell gets trapped in the phone booth and breaks the window to get out. When he breaks the window, notice that the phone booth is no longer located on the sidewalk, it is now magically next to a building. (00:14:45 - 00:15:25)
Other mistake: Helen is holding the cup of rich "cocoa" that Markie supposedly just drank. Helen says, "I thought she'd finished her cocoa, and here it is untouched." Close-up on the "cocoa," which is clearly (so to speak) nothing more than water. (00:12:10)
Mr. Dingle, the Strong - S2-E19
Continuity mistake: When Mr. Dingle gets ashes from Don Rickles' cigar on his suit, the ashes disappear moments later.
Mr. Dingle, the Strong - S2-E19
Visible crew/equipment: In the scene where Dingle is waking up to the alarm clock, you can see a camera shadow moving over the bed.
Revealing mistake: When Jimbo lifts the bed up using his mind, you can see the cables pulling it up.
Mr. Dingle, the Strong - S2-E19
Revealing mistake: When the reporter is talking into the microphone, you can see that the microphone is not hooked up.
Factual error: Captain Riker and Lt. Fitzgerald are wearing their insignia, which is incorrect. Officers serving in front line units did not wear their insignia because it identified them as high priority targets for Japanese snipers.
Mr. Dingle, the Strong - S2-E19
Revealing mistake: A close-up shot of the man Dingle is lifting over his head shows part of the lifter's face - revealing that an actor other than Burgess Meredith is used here.
Mr. Dingle, the Strong - S2-E19
Audio problem: The sound of the table breaking begins before Mr. Dingle hits it.
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.
A Thing About Machines - S2-E4
Visible crew/equipment: When Finchley is being chased by his "driverless" car, you can see the driver crouching down at the wheel.
Continuity mistake: When the Ground Crewman runs after Lt. Decker, he reaches him just as Decker is climbing onto the plane. You see the Ground Crewman put his hand (or just about to) on Decker's upper left arm. When they cut to a closer shot, the Ground Crewman's hand is in the process of moving up to Decker's arm.
Continuity mistake: When Decker first gets out of his plane, Maj Wilson begins to question him. Decker's hair is neatly combed. When Wilson asks him "Are you French?" the shot changes to a closeup of Decker only. His hair is now disheveled in the front and hanging down on his forehead. The next shot returns to the wider angle and Decker's hair is more neatly combed again, as it originally was, not hanging on his forehead.
Revealing mistake: As Peter goes to the fishers, the pair shown on the bridge behind him are obviously photographs.
Mr. Dingle, the Strong - S2-E19
Revealing mistake: Before Dingle tries to lift the building, a crack can already be seen in the ceiling beam.
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.