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.
Angel of Mercy: Part Two - S1-E4
Character mistake: When Lenore Osgood is speaking on the phone with Charles Wainwright about killing Dr. Hanover, she mispronounces "Larynx" as "Lar-nix."
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 X-ray shown when Ruth see Cade's body is placed in the wrong way. It should have been a mirror image. (00:57:56 - 00:59:06)
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: Logan tells Heather that Mario Kart (Double Dash) has an online mode. It does not.
Devil Music - S5-E4
Character mistake: When they pulled the bullet out of the wall of the Five and Dime, Danny says that it was either a .40 or .45 caliber. The .40 caliber was not produced until 1990, 37 years after the date the crime took place. (00:30:00 - 00:35:00)
Character mistake: OA says that Vickers went to Erasmus University Amsterdam, but the Erasmus University is in Rotterdam not Amsterdam. (00:07:03)
Character mistake: Sasha refers to the 'murder' on Thursday 4th June 1982. The date in question was on a Friday.
Character mistake: The leader of the Purple Knights says that they would only be bike riders if they couldn't tell which gender someone was by their hair. This is a major mistake, because if you look at the hair of the Purple Knights, it's incredibly easy to tell which gender someone is.
Episode #1.3 - S1-E3
Character mistake: Richie Gulliver is referred to as Rory Gulliver on the newspaper headline. As he's supposedly a very well-known Member of the Scottish Parliament, it's unlikely a newspaper would make a mistake like this.
Episode #2.3 - S2-E3
Character mistake: DS Maxwell comes to Katy's house to interview her but when he introduces himself he says "DI" Maxwell.
Character mistake: Jessica is looking at a bank statement on the computer. "Withdrawal" is misspelled as "withdrawl." (00:15:45)
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.
Flashpoint - S1-E5
Character mistake: Chief Pope threatens to take away Lt Flynn's stripes. Lieutenants don't have stripes.