Continuity mistake: When he introduces himself to Millicent inside the train station, Paul is wearing a dripping wet raincoat. It stays wet in the close-ups, but in the next several inter-cut two-shots, it's completely dry. (00:11:15)
Continuity mistake: In the final scene, the position of the silver dollar lying next to Franklin's hand changes several times between shots. (00:23:45)
Continuity mistake: Renard gets his bottom wet from sitting down and tying his laces on his new shoes. But after he is hit by the car, his trousers are dry.
Continuity mistake: When Nan first swerves to avoid The Hitch-Hiker, her 1959 Mercury briefly turns into a 1957 Ford. It also changes from a light to a dark color. (00:17:15)
The Lonely - S1-E7
Continuity mistake: Allenby brings Corey a stack of paperback books. He's holding them with the back covers facing out until the shot cuts, and then the stack of books has reversed itself in his hand: the back covers are now facing inward. (00:20:30)
Continuity mistake: Henry closes the door of the rabbit hutch, but it bounces back open. When he turns back to the hutch a minute later, though, the door has closed itself. (00:16:30)
Continuity mistake: No one drinks much lemonade, so there's neither time nor need for Eve to refill the pitcher during the brief cut to a scene on the porch. Yet after she has emptied its contents into the glasses on the tray, the lemonade pitcher refills itself. (00:15:15 - 00:19:10)
Continuity mistake: As the hour is striking midnight, Maggie's toy robot turns itself on and walks past the alarm clock on her bureau. After a cut to Lou and Mr. Death, the scene returns to Maggie's room, and the robot walks past the clock again. (00:22:00)
Continuity mistake: After Franklin falls through the window at the end, he lands on the pavement below - on top of the broken window frame. Next shot, when the police are examining the body, the window frame has moved out from under Franklin and is lying about a foot away. One shot later, though, it's back in its original position underneath him. (00:20:00)
Continuity mistake: Hall leaps through the plate glass window. In the interior shot, he breaks the glass and is 3/4 of the way through the opening (up to his knees) - until we cut to a view from outside the window. Then he's just crashing through at shoulder level. (00:22:45)
Continuity mistake: Walter crumples the prescription slip and tosses it onto the bed - but in the next shot, it has disappeared. (00:05:15)
Continuity mistake: When Mr. Bookman is leaving his apartment to get away from Death, there is a note tacked to the door that is about level with his head. In the next shot, he's out in the hallway locking his door and the note has moved up to about 6 inches above his head. (00:12:35)
Continuity mistake: When Ferris is in the phone booth, he tries to get the operator but then hangs up the phone. He then scans the Town Square. The camera pans counter-clockwise and the receiver is nowhere in sight.
A Passage for Trumpet - S1-E32
Continuity mistake: When Joey goes into the bar, being invisible, after pouring himself a drink, the bottle rotates on its own accord.
Mr. Denton on Doomsday - S1-E3
Continuity mistake: The rum stains on Denton's shirt move in between shots before he starts singing "How Dry I Am." (00:01:45)
Continuity mistake: When Decker first exits the aircraft, there is a jeep immediately behind it, a service truck behind the jeep, and a USAF F-100 Super Sabre jet in the background. However, when Maj Wilson escorts him away from the plane, the service truck is gone and the F-100 has been replaced with a large transport aircraft.
Continuity mistake: After Nan sees Hitch-Hiker for first time and she starts speeding away, she has clear road both in front and behind her. But just seconds ago, a mechanic told her to follow him to his shop so he could change her tire. Where did he go?
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.
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.
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.