Revealing mistake: When Queen Elizabeth arrives in disguise, Blackadder welcomes her and is about to open the door to the closet, but you can see the door is being pushed up from the inside, probably by a crew member. (00:16:50)
Revealing mistake: When Dori types in an inquiry into the computer it is very obvious that her typing is absolutely nonsense - she types the same three letters in a row over and over again, and never presses Enter. (00:19:05)
Revealing mistake: Abe Lassen's hair color changes throughout the episode.
The Affair - S1-E4
Revealing mistake: The attempt on Rodriguez's life is quite phony looking; leaving aside the trope of a person who wants to avoid being murdered by a car by trying to outrun it instead of getting out of the way (the first semi-POV of the car does a terrible job at that, since the car looks much closer to The Victim and slower than it should be, and wide room for Rodriguez to escape sideways), the impact does not happen and the stuntman jumps into a pile of garbage without anything remotely close to connecting. (00:32:00)
Monster in the Playhouse - S1-E9
Revealing mistake: As Reba the Mail Person exits the Playhouse, she goes past the window, and you can see her exit the sound stage through a door painted the same as the background.
Revealing mistake: While Holmes and Watson are investigating the crime scene, there is a shot of them that shows the dead man's hand. His hand is visibly shaking, revealing the actor is struggling to maintain the position of his hand.
Revealing mistake: When Alicia slaps Bea, her hand actually misses Bea's face.
Revealing mistake: The extras and actors are made to appear to be naked as they live in a nudist colony, but many of them are wearing some kind of undergarment.