Character mistake: The note Six hands the "access man" misspells the word "receipt" as "reciept." He's supposedly a "think tank" genius, so really should be able to spell better than that. (00:27:30)
Character mistake: Troy calls for the "Twistornado" but his card reads "Windrive"; the cards have always read exactly what the rangers called for.
Character mistake: Dr Smith who has some of The Robot (ie, bravery and courage) quotes The Fall of The Light Brigade but mistakenly says "into the valley death rode the five hundred" when it is actually 600. Both Dr Smith and the Robot would know this very famous poem's most well known line. (00:44:45)
Suggested correction: There's nothing to suggest they would know the poem exactly, especially since you yourself don't even know the actual name of the poem. It's "The Charge of the Light Brigade."
Character mistake: There is a spelling error in the newspaper that Sakurako Sawatari is reading in one episode: the word, "admits" is spelled "adwits." (00:01:00)
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.
Takishîdo wa kaze ni mau - S1-E1
Character mistake: During Lucky's initial display of power at the gates of the settlement, he fires a cannon shot at the building and shouts (in the English dub) "How do you like that? Bullseye." There's a view of the building and you can read the horseshoe sign; "Evergreen SHOPING Mall." (00:07:15)
Second Time - S2-E13
Character mistake: When Kiera is begging one of the Freelancers to send her back she says she could "prevent Liber8 from ever coming to 2077." She should have either said "coming to 2012" or "leaving 2077."
Character mistake: The language peculiarity of the series refers to any wheeled vehicle as a "roller." The character "General Tak" accidentally breaks the language rules near the end of the episode and uses the word "car."
Character mistake: When Rich refers to the film showing Davis (decades ago), he figures they were in "Asia... Mongolia or somewhere." However, the film cannister had "Tibet, 1937" written on it - important enough to show the audience, but not for the character to read? (00:40:25)
Character mistake: The date on Louise's plane ticket to London is listed as "Thursday 16 February 2017", but the month "February" is missing the U, misspelling it as "Febrary." (00:15:56)
Children of Earth: Day One - S3-E1
Character mistake: Lois says that Colonel Aduya's uniform "isn't British Army". In fact, it is entirely (and accurately) British Army with the exception of the small UNIT badge over the pocket.
Character mistake: When we first meet Gadus, he pronounces his name "Gay-dus", but later on in the episode Maran calls him "Gad-us".
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: On the witness stand, Janet Wilk speaks of moving "here to Lincoln City", but the episode takes place in Jackson City.
Character mistake: Throughout the series, General Ross refers to Gabe Jones as Gabriel. Someone of Ross' military credentials would not address another government agent by their first name. He would call him Agent Jones or simply Jones.