
Deadeye Dick - S5-E9
Character mistake: Bob's father's name is Harry Foley according to Granger and the end credits. But James Drury apparently forgot this in one scene, where the Virginian addresses Harry as "Tom."

Character mistake: Tom Mason makes references to smaller armies defeating larger ones, of which history is rife with examples. He cites the Scottish defeating 'the British' at the Battle of Stirling Bridge. 'The British' did not exist at that time. The Scots administered a beating against the English in the Scottish War of Independence, against the Earl of Surrey, under Edward I. Someone with his level of knowledge would know that.

Character mistake: As Eddie Haskell and Lumpy Rutherford return from the washroom to Mr. Gannon's history class, Mr. Gannon calls Eddie "Louis."

Character mistake: When Jet tells Katara and Aang to waterbend the water from underground in the geysers, Katara states that she has never waterbent on water she couldn't see before. However, six episodes prior to this, in 'The Warriors of Kyoshi', she waterbends the water out from Aang's lungs to save his life.
Suggested correction: That was a moment of desperation on her part, and she probably doesn't think of it/think she can do it again without the same desperate impetus, Furthermore, the water in Aang was only a small amount and very close anyway.
Regardless of if she did it in desperation or not, she did use bending on water she didn't see. The mistake isn't suggesting anything about Katara's ability to waterbend unseen water, the mistake is only in regards to the statement Katara made about never using bending on water she can't see. And for Katara to forget the one time she used bending on water she didn't see would qualify as a character mistake as well. Now if she made the statement "I don't think I can do this" or "I've never used bending on underground water", etc, that would not be a character mistake.

Character mistake: At the end of the episode, after Sarah has been tricked into revealing her plan and is rather obviously going to go to jail, Tru tells her that she "should have taken half," meaning that she should have settled for half of Andrew's money in a divorce instead of trying to get all of it by having him murdered. But Tru seems to be forgetting that Sarah has been trying to divorce Andrew all along, and it's Andrew who has stood in the way of that. Sarah would evidently have been perfectly happy with half, but Andrew prevented it from even being on the table for her, so Tru's comment doesn't make any sense.

Character mistake: Horatio writes the symbols for sulfuric acid, H2SO4, on a clear board. Both numbers should be subscripts but he writes the 4 as a coefficient (which precedes the name of the acid but he writes it after), suggesting a lack of basic chemistry knowledge.

Touchstone - S2-E14
Character mistake: The team are finding out who could have stolen the weather device from Madrona and find an energy spike at the same time SG2 are on a mission. "But SG2's mission is galaxies away from Madrona" Says Teal'c. At this time the only missions the teams could go on was in our own galaxy and couldn't be galaxies away.

Character mistake: When the Brady kids are practicing for the talent show, instead of saying, "Come on, Pete," Marcia says, "Come on Chris," which is the actor playing Peter's real name (Christopher Knight). (00:14:30)

Character mistake: When Faith arrives in LA she is carrying a bag. She puts it on the ground and then steals a man's jacket and wallet. Afterwards however, she leaves without picking up her bag.

Character mistake: When Bree calls the police when she hears a noise downstairs, she says she lives at 4355 Wisteria Lane when her address is in fact 4354 Wisteria Lane. 4355 is the Scavo residence, not the Van De Kamp residence.

Simpsons Already Did It - S6-E7
Character mistake: Butters says that he watched "all 132 episodes" of the Simpsons; at the time this episode aired, 291 episodes of the Simpsons had been produced and aired.
Suggested correction: Butters is always shown as being a bit dim and slow. As a kid it's easy for him to make a mistake in thinking that there was only 132 episodes.
That's why it's called a "character mistake"; also, Butters is certainly naive, but he's hardly what I would call "dim and slow."

Character mistake: Winona says that Jason killed a penguin on their trip to the Arctic. This is impossible because penguins only live in the southern hemisphere.

Character mistake: At the very end of the episode Tara tells Glenn that her sister and nephew were not supposed to be there. Tara had a niece not a nephew.

Rudy's Walk on the Wild Side - S6-E18
Character mistake: At the beginning, when Vanessa is begging for money from her dad to buy a CD, Cliff says she can clean the garage. But the Huxtables live in a brownstone townhouse and brownstones do not have garages.

Character mistake: Hayley is on the phone in the car with Alex and she's holding her phone upside down.

Character mistake: During the scene of the dinner, James (Raquel's father) states that he was in the Royal Navy and was "First Officer" (1/O). The Navy does not have this rank since it is a Merchant Navy rank. The rough equivalent of this is Lieutenant in the RN and Albert would've known this but didn't mention anything. It is also extremely unlikely that an officer the RN would still be Lieutenant after doing his full quota of 12 years service.

Character mistake: Series 1, Episode 3: When Alex tells Ray she will re-trace his steps for clues linking to the murder of a girl, he says, "Don't worry, lads! Wonder Woman's here!" Alex replies, "FYI DI Carling." Ray is a DS, not a DI.

Character mistake: When Kate mentions James Bond, and DiNozzo lists the actors who have played him, he forgets Timothy Dalton. As a self-proclaimed film buff, that's not a mistake he would make.

Well Bargained and Done - S1-E2
Character mistake: Tybus says he has a lance of 5 mechs. In Battletech, a lance is 4 mechs. While a Clan star does have 5 mechs, Tybus is an Inner Sphere character.