Character mistake: When talking about poker Jimmy asks Dave "What are the chances of getting five of a kind of the same suit?" The most you can get is four of a kind and they would be all different suits.
Suggested correction: Jimmy says "in the same suit" which is slightly different than "of the same suit." It was just a weird way of saying the odds of getting a flush. Lisa replies with 504.8 (the odds of getting a flush). In poker lingo, 3 or 4 of a kind is taken to mean same value since 3 or 4 cards in the same suit isn't anything.
Suggested correction: Five of a kind is possible when using one or more wild cards, such as Jokers.
Character mistake: When Geoffrey serves tea after his sassy cough at Vivian's sentence about High Tea not being a sacred institution, the actor messes up when it's time to actually serve tea, with a napkin getting caught in the teacup saucer. Granted, accidents do happen, but it's quite uncharacteristic for the perfect butler Geoffrey is portrayed to be, and simply a flub by Joseph Marcell. (00:17:45)
Character mistake: When Ryan is recreating the chess game he and Mandy played, he has the chessboard setup incorrectly. He has the dark square on the lower right corner when it should be the white square. He was a junior grand master and would know better, especially since he had the board set up correctly when they were playing.
Character mistake: When the gang split up to look for the missing Billie and Tiger, Scooper says "me and Sticks will look up here" and goes upstairs but Sticks goes with Brains to search the ground floor - it's Spring that goes upstairs with Scooper.
Looking for Mr. Goodbrain, Part 2 - S3-E13
Character mistake: When Liv and Clive are talking to Chase about Katty, Liv tells Chase he had a cocktail napkin with Katty's phone number on it. However, it was only Katty's hotel room number that was on the napkin, which Liv saw.
Character mistake: Edith says in a story that Archie has a brother Phil. In actuality Archie had 1 brother, Fred.
The Hairy Scare of the Devil Bear - S1-E8
Character mistake: Velma says bears only have four claws. Wrong, they really do have five claws.
The Blood of a Jeannie - S5-E7
Character mistake: Jeannie tells Tony that she can't blink, then immediately blinks.
The Wedding - S8-E23
Character mistake: When Roseanne, Darlene, Jackie, Bev, Becky, and Nana Mary are dressing for Darlene's wedding, Nana Mary comments that all of them were pregnant when they married. However, Becky, was not pregnant when she and Mark eloped and they never had children together. Roseanne was not pregnant before marrying Dan. When the series began, Becky was 13 years old and Dan and Roseanne had been married 15 years.
Character mistake: Levitt is often seen wearing a cap device as a shield (badge). This is a big no in the NYPD.
Character mistake: Dexter's father says he'll stunt jump over four school buses, but only three are shown.
God Is in the Details - S2-E10
Character mistake: When Diane quotes the scripture, she says "Revelations." However, it's just "Revelation." Someone as smart as her who has read the New Testament (or heard it quoted) would know the correct word.
Charlie and Dee Find Love - S8-E4
Character mistake: Near the end, when Charlie is leaving to be with the Waitress, Ruby says she wasn't using him "like Charlie was." She's talking about her brother and meant to say "Trevor."
Character mistake: Eddie, Spudgun and Dave Hedgehog all appear worried at the fact that the devil takes "virgin's blood." However, it is apparent later in the episode that the 'devil' is in fact Dave Hedgehog's daughter, meaning he isn't a virgin.
Suggested correction: Also, Eddie previously slept with the Third Viscountess of Moldavia when Richie's back alley kidney donation backfired and he collapsed, so he wasn't a virgin either, but reacted as though he was.
Although theoretically correct, bear in mind that neither Eddie or Dave Hedgehog aren't particularly bright, and likely forgot they weren't virgins.
Hedgehog's daughter could have been adopted.
Character mistake: Bret fires at "John Wesley Hardin" four times, but the doctor and all the witnesses say there were three shots.
Lady Florence Craye Arrives in New York (or, the Once and Future Ex) - S4-E2
Character mistake: Cheesewright is trying to convince the police to raid the charity ball because alcohol is going to be served. The police chief tells him they stay out of private affairs and Cheesewright replies "The law's the law!" Prohibition made illegal the sale and transport of alcohol, but people were still allowed to have it in their homes or private functions. No laws were being broken. (00:33:30)
In the Waiting Room of Estranged Spouses - S2-E6
Character mistake: The former Marine, Spenser, refers to himself as a soldier. A Marine would never do that.
Character mistake: James mentioned to Florida that he always knew his father was alive (after claiming to Florida he was dead in the past). But since James hasn't seen or heard from him in 35 years, there would really be no way for James to know that his father was still alive for sure - more like just a guess than certainty.
Cat on a Hot Steel Beam - S1-E60
Character mistake: As the fire truck darts out from a back alley, the sign on a nearby gift shop window reads "gift's" when it should be "gifts".
Character mistake: In the episode where Henry has overdue library books, they are overdue by 5 years and 23 days. Both Henry and Monroe say in the episode that the fine is around $1000 (based on 10 cents per day due 5 years 23 days)... But in reality, using that calculation, the total would come to only $185, not $1000.