Revealing mistake: In the close-up of Frost's hand while the doctor is stitching up his wound, you can see the delineated edges of the latex make-up patch used to simulate the injury. (00:12:30)
Continuity mistake: The water level in the dispenser rises and falls by itself several times throughout the episode. (00:08:05)
To See the Invisible Man - S1-E40
Continuity mistake: In the cafeteria, the "invisibility" mark on Mitchell's forehead has moved to a higher spot than it occupied in previous scenes. (00:05:00)
To See the Invisible Man - S1-E40
Visible crew/equipment: When the woman ignores Mitchell and rushes into her apartment building, the glass door she opens reflects the camera, crew and studio lights. (00:06:20)
Other mistake: Veteran actor Elisha Cook's name is misspelled "Elisa Cook" in the opening credits. (00:01:00)
The Little People of Killany Woods - S1-E34
Visible crew/equipment: When it's opened for Mulvaney, the hardware store's glass-paned door reflects several large, round studio lights. (00:06:05)
The Beacon - S1-E26
Plot hole: Barrows introduces himself as "Dr. Dennis Barrows," and Teddy asks, "What's a doctor?" As the isolated villagers have never heard of doctors, Teddy would have no way to know that "Doctor" was a title/profession and not simply part of Barrows' name. He should have asked, "What kind of a name is Doctor?"
Song of the Younger World - S2-E20
Factual error: It's the 1800s, but Amy's skirt has a 20th Century zipper running down the back. (00:05:15)
Song of the Younger World - S2-E20
Factual error: The 19th Century reformatory has modern electric light bulbs hanging from the corridor ceilings. (00:21:10)
Time and Teresa Golowitz - S2-E18
Continuity mistake: As they talk, Prince and the pianist stand beside the apartment wall that's covered with Broadway show posters. There's no break in their conversation, but when the shot cuts, they're across the room in front of the window. (00:03:15)
Continuity mistake: Willy pulls one bottle of champagne from the full case and gives it to Mrs. Cooper. In the next shot, as he heads down the stairs with the wine, the case is full again. (00:10:30)
Answer: Poisoned food, heart attack from eating too much food, or he slipped in the shower. The list is endless.