Continuity mistake: When the decrepit Mr. Holt gets his new young body (briefly necessitating a different actor in the role), his German accent mysteriously disappears. He gets it back when he returns to his old body. (00:21:00)
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.
Continuity mistake: The clock in the booth with a broken face is shown in a distant shot, then in a close-up, where more cracks appear in it than before.
The Trouble with Templeton - S2-E9
Continuity mistake: At Freddie's speakeasy, when Laura lifts Barney's script from the table, she begins to fan herself. In the wide shot, the script's titled top page with corner diagonal stripes is gripped under Laura's four fingers, with the blank back page at her thumb. It cuts to a close-up, and now the script is gripped in Laura's hand the opposite way, with the top page at her thumb (the back page is blank).
Continuity mistake: When Ferris enters the cafe and announces they have a customer, he still has the stick in his right hand. He lays the stick on the counter as he begins to climb across. As the camera pans, and then back as he gets on the counter, a menu is now covering the stick.
Continuity mistake: At the beginning, The main character is driving a car and hits a bicyclist and kills him. The inside shots from the car show the driver's window closed. The outside shots show the driver's window open.
Continuity mistake: During Rod Serling's opening narration you can see over his shoulder part of the outline of the portal to the 4th dimension, which would be drawn there later in the story.
Continuity mistake: After McNulty freezes the office, a co-worker is getting water from a faucet, and the water is frozen in motion, but right before McNulty unfreezes the office, a female co-worker is in the background at the faucet with no water coming out of the faucet.
Continuity mistake: After sounding the "alert" for his guests, Raden turns around to fully face them, and as he addresses the Reverend, from the back his hand is gripping the arm of the chair. In the the next moment, there is a frontal shot, and Raden's hands are folded on his lap.
The Odyssey of Flight 33 - S2-E18
Continuity mistake: When the jet is preparing to land in 1939 New York City, the view of the crew from the back of the cabin forward shows the airliner captain wearing his headphones, but the next instant close up of him shows him not wearing the headphones.
Nick of Time - S2-E7
Continuity mistake: Don Carter is holding a glass of water at the lunch counter. When the shot cuts to him and Pat, his hands are clasped together, empty.
Nick of Time - S2-E7
Continuity mistake: As Don and Pat leave the diner and another couple enters, there are two glasses of tea that have changed position on the table with the Mystic Seer, and two chairs have suddenly materialized at the booth they were using when the other couple arrive to use the Mystic Seer machine.
The Odyssey of Flight 33 - S2-E18
Continuity mistake: The radio operator's hand is gripping a bar behind the airliner captain, then in the next shot it's not.
The Changing of the Guard - S3-E37
Continuity mistake: While at the window listening to the Christmas Carolers, the eyeglasses Professor Fowler is wearing disappear and reappear, depending on the camera angle.
The Odyssey of Flight 33 - S2-E18
Continuity mistake: There are three scenes of the jet flying above a thin layer of clouds. The same piece of footage is used each time.
Continuity mistake: Death has a bag full of purchases made from Lou. As they walk off, Death's bag disappears.
Continuity mistake: In the opening, Mr. Bookman has a toy replica of Robbie the Robot in his left hand in the close up, but a bottle in it a second later.
Continuity mistake: In the vault, the book Mr. Bemis puts down flips open a moment before the atomic blast. After the explosion, the book is closed again.
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)
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.