Continuity mistake: In the early scene when Bevis tumbles down the stairs of his apartment, a little boy watches and then holds his hands over his eyes. In the next shot, the boy is shown walking outside, but then the camera cuts and he is shown back inside, his hands still over his eyes.
Continuity mistake: When Mr. Bevis starts his car, a girl with shoulder-length hair runs over with other children to help push it. In the first shot she's at the rear bumper but in the following shot she's beside the passenger door and there are different kids at the rear bumper. (00:03:25)
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.