Revealing mistake: When the band in the nightclub performs the made up song "Mr. Music Man", the suave Mr. Stone, the musician Miss Fisher ends up dancing with, is doing one heck of an hilariously incompetent job at faking to play an instrument, basically playing air-banjo strumming about 3 inches above where the chords are, and wildly off tempo. In the closing bit of the song (as the singer sings "To sin") he even moves his hand at the side of the strings and not above them. (00:03:30)
Revealing mistake: When Nathan and Audrey are sitting at the table in The Grey Gull, the extra in the background can be seen bringing a loaded fork inches short of his mouth then fake chewing. This happens a few times before cutting to the ending credits. (00:40:05 - 00:40:55)
Episode #1.7 - S1-E7
Revealing mistake: When the guitarist punches the bass player in the face you can see him miss. (00:50:02)
The Two Deaths of Jamie B. - S2-E4
Revealing mistake: When Naomi shows Kirsten the money, you can tell it's fake. Not only are the serial numbers all the same, you can read "this note is not real it is to be used for motion pictures."
Ashes, Ashes - S1-E6
Revealing mistake: It's pretty obvious that Scott Glenn, the actor playing Stick, just has his hand wrapped up to look like it has been cut off. Both his hands are at equal length when his arms are down by his sides.
Revealing mistake: When the thief places The Blue Carbuncle in the goose's throat, it's obvious he actually doesn't put the gem in the bird's mouth. He pretends to, but then drops the gem into his other hand. This is all visible in the shot.
Revealing mistake: In the sequence with Zeus and Apollo attacking the intruders, the padding of the jackets' arms they are sinking their teeth into is very noticeable. (00:32:15)
Episode #1.4 - S1-E4
Revealing mistake: The tabloid story with the plight of the Latimers just came out, and various characters are looking at it. In the bit when David Tennant tosses on the desk his copy of the Herald, the second paragraph of the second column goes "Sitting in the family home, surrounded by pictures and mementos of Danny" etc. It is the same text that was at the very beginning of the article when the store owner was looking at it. The newspaper is a prop with the same text in a loop. (00:35:00 - 00:36:30)
Revealing mistake: "Who Killed the Rest?" The boat we see speeding toward shore explodes - but in the brief shot of it just before the detonation, the substitution of a model is apparent. The two vessels don't look anything alike. (00:02:00)
Revealing mistake: The left pinball in the arcade (which later disappears) has the body of a "Star Trek TNG" machine - but the backglass is purely fictional. (00:17:45)
Revealing mistake: Halfway through the show, the officers get a flat. As Malloy is getting ready to jack up the car, Reed starts using the lug nut wrench to loosen up the nuts. He repeatedly turns the wrench clockwise, which would tighten the nuts.
Revealing mistake: Paul Devildis calls the bank to discuss his restructuring plan. During the shots of the two bankers, on the desk is a notebook-sized, plain brown box. It is very distinctive as it is blank except for a single square white label on the front. Later in the episode Paul delivers his restructuring plan with the bomb inside to the bank. It is in this same box.
Revealing mistake: In the scene where Cooper takes the homeless man's photo on his iPhone, if you look to the bottom left of his iPhone's screen where it shows pictures that you have already taken, you can see that the homeless man's photo has already been taken, indicating that perhaps this scene was shot a few times, and the photos taken during those scenes were never deleted.
Revealing mistake: It's a valiant effort, but the scenes of Sherlock & Irene in a London street are shot in New York. Not only is the architecture wrong but you can see a U.S. pedestrian crossing signal over Irene's shoulder. (00:16:15)
Heart of Ice - S1-E3
Revealing mistake: When Batman - disguised as a security guard - opens his utility belt, the belt opens and shows a configuration of buttons and a split-second later, a key card materializes out of thin air in front of the buttons. (00:11:30)
Revealing mistake: When Denise is showing Brad how to kiss, the first kiss is a typical "stage kiss" with their lips pretty clamped shut, but she then details what he's doing wrong with his tongue, which clearly wasn't at all involved with the sort of kiss they just shared.
Revealing mistake: When Lizzie awakens on the morning that Edith gets released, Edith doesn't respond and Lizzie goes to her bed to "mourn" the passing of her friend. Except that Edith is still breathing.
Revelations - S1-E10
Revealing mistake: When Kieran looks at his phone in the car, the image of Emma calling him is upside down. The image was added after the filming was done.
Revealing mistake: Near the end of the episode, when Dr. Ogden and Murdoch look closely at Lukas' dead body (right before the candle scene), the "corpse" takes a deep breath.
Lead Horse Back to Stable - S1-E11
Revealing mistake: When Danny and Colleen are fighting in the rain at the end of the episode and Danny starts explaining how they should stop fighting, raindrops from the camera can be seen dripping from the top left of the screen.