Character mistake: While testifying during his murder trial, George Vogelman says that he's gone on dates but has never been in a relationship. However, when he sued Ellenor during season 2's "Sex, Lies and Monkeys," he says they discussed his first marriage and his kids, which contradicts his later testimony. While it's certainly possible he could have been lying about having a family, that would mean he was lying to Ellenor about it, but as his lawyer, she takes him at his word as if he didn't have a history of lying.
Character mistake: Mahershala said the child found in the cement had "osteoportrosis", instead of osteoporosis. Then the grief counselor repeated the same incorrect word.
Suggested correction: They said "osteopetrosis," which is a different medical condition from osteoporosis. Osteopetrosis is a genetic condition that causes overly dense, brittle, and misshapen bones starting in infancy.
Character mistake: Logan tells Heather that Mario Kart (Double Dash) has an online mode. It does not.
Character mistake: In the epilogue, Charlie illustrates the relationship of mathematics to real life by discussing the golden ratio and its presence in a host of real-life situations, including the shape of a nautilus shell and the distribution of petals in a flower. These claims are disputed by some mathematicians (see http://en.wikipedia.org/wiki/Golden_ratio#Nature), and the one about the nautilus shell one is untrue (see http://en.wikipedia.org/wiki/Golden_spiral#Spirals_in_nature). It's possible Charlie is just repeating what he has read or heard without investigating it for himself, but this is uncharacteristic of him.
Character mistake: Sasha refers to the 'murder' on Thursday 4th June 1982. The date in question was on a Friday.
Character mistake: Nick asks Janette if she's ever turned anyone else into a vampire - an odd question, considering the fact that he already knows she has. He was there when she brought the baroness across in the 18th Century flashback sequence for "If Looks Could Kill." It's even odder that Janette tells him she's never done it, since she knows that Nick knows she has. Apparently, the only one not in the know here was the scriptwriter.
Character mistake: While filming the cheerleader performance, Jasper refers to his inability of using computers ("We're gonna put this on YouTube as soon as one of us figures out how to use a computer!"). Earlier in the series, however, Jasper ordered himself a Russian wife online, so this statement is definitely off-character.
Character mistake: Lorraine mistakenly tells Denny to "call 999" instead of 911, and when asked about it by Katie, denies having ever spent time in the UK (later revealed to be a lie). But this isn't some high-pressure slip of the tongue, she's highly intelligent and has been in America for a decent length of time, is working hard to maintain her facade of being born and bred American, so there's no way she'd slip up over such an obvious thing.
Character mistake: Dr. Sloan and Quinn are in the victim's apartment. Right before Dr. Sloan opens the door for the old lady witness to ID Quinn, Dr. Sloan says, "saw a man visiting Holly the night before he died." Holly is a woman. Dr. Sloan should have said "she." (00:33:51)
Character mistake: In one episode, John, Meldrick and Tim are called down to their bank because they're getting a business loan to buy the Waterfront Bar (the bank's policy is to give good news in person). They start arguing and Tim announces at one point that "I've got a platinum card, Frank", which is marvelous, except he's talking to Meldrick.
Character mistake: Maxwell translates his famous line "And loving it' into the German 'Und damit gefreut'. Agent 99 who claims to speak German fluently confirms it. This translation is both far away from the meaning and doesn't make any sense at all. The right translation is 'Und liebe es'. (00:09:50)
Character mistake: When Walker and Satch are in the car looking for Walker's son, Walker tells Satch his son is 17. Afterward, when they are out on the streets, Walker asks some people if they have seen his 18-year old son.
Character mistake: Upon finding the Spanish flu virus missing, Hardison freaks out about it killing 50m people 100 years ago, saying it would be even more deadly today due to the higher population. There's no reason to think so - the death toll in 1918 was massively exacerbated by the aftermath of WWI. Not to mention today we have vaccines, plus most deaths then were actually caused by bacterial pneumonia, which today is easily treated with antibiotics.
Flashpoint - S1-E5
Character mistake: Chief Pope threatens to take away Lt Flynn's stripes. Lieutenants don't have stripes.
Six Forgotten Warriors Chapter 4: The Six Fight Again - S5-E5
Character mistake: When the Red Skull reemerges from the vortex, he sees Chameleon and acknowledges him as his stepson. However, only moments before this, Kragov explicitly stated that the Chameleon was more like an adopted son to the Red Skull.
Character mistake: The doorman tells Ike that Jimmy Shoes and the prostitute left in a '55 Chevy, the car is a '56 Chevy.
Character mistake: Nathan suggests to Dwight and Audrey that maybe he should shut down the meeting of troubled people. As chief, he should know he has no authority to stop citizens from assembling.
One Good Man - S3-E6
Character mistake: After Patton's ex-wife pushes him off the balcony and he lands on the researcher with the gun and the rest of the team come in, someone asks him if he is OK. He says that he is fine, nothing is broken. Other than his arms, ribs or neck how is he going to know that? He is already paralyzed. He can't feel anything.
The Dark and Bloody Ground - S1-E3
Character mistake: Clyde Russell tells Rockford to meet him at his place in "Ambazac Road in Bel Air." The name of the street in real life is Ambazac Way. (00:38:20)
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.