Other mistake: When McNulty uses the stopwatch to rob a bank, he goes through a small wooden door and past the employees. With time frozen, the small door should have stayed open but immediately swings shut.
Other mistake: When Lillian calls Oliver, she tells him that the car stalled at 3rd and Park - the original scene of the accident. Later, when Oliver goes into his garage in the middle of the night, the car turns on its radio and goes to a news broadcast about the hit-and-run that took place at 3rd and Elm.
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.
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)
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.