The Eye of the Beholder - S2-E6
Other mistake: For someone whose entire head has been bandaged for several weeks, Janet Tyler's curly hair is remarkably unflattened when the bandages are finally removed, and her thick mascara isn't smeared in the least. (00:00:15)
The Odyssey of Flight 33 - S2-E18
Other mistake: One of the crew members looks at the air speed indicator and states they are going over 2100 miles per hour. Why would a subsonic plane have an indicator that reads to 2100 mph?
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.
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.