The tattoo on Lucas's chest is a depiction of the William Blake etching "Ancient of Days", a reference to the character's connections with William Blake.
Tattoos on Lucas North's body:
Script: Dum Spiro Spero (While I live I hope) on back of neck; Gnothi Seauton (Know thyself) on abdomen; unidentified three letters on lower back; unidentified long passage on inner left arm.
Graphics: eight cupolas with crosses on upper back, representing eight years of imprisonment;
tallship on upper right arm, representing aspiration for freedom; star on left upper arm meaning will not cooperate with authorities, and had been through the maximum-security prison; handcuff (?) with a short chain on right wrist representing imprisonment. The main picture on his chest could be interpreted as religious iconography (world creation?).
Bakhshi says that there are six permanent members of the UN Security Council and Iran wants to become the seventh, in exchange for a deal on the peace agreement. There are actually only five permanent members: the US, the UK, Russia, France and China.
Adam says that the three people being interviewed on the current affairs programme were politicians. Of the three, only Ruth Chambers, the Foreign Secretary, is a politician. Bob Hogan is a spy and Bakhshi is a diplomat.
When Sally is checking what Neil has downloaded off her workstation, some of the previous downloads have spelling mistakes in them. 'Updates' is spelt 'Udates' ("Virus Udates 7.3") and 'continued' is spelt 'continude' ("IRA's continude threat")
The software Malcolm is using to track the hotel guests has some spelling errors - American guest Styles is referred to at one point as "Secretary off State Styles"
Goof: Traynor Styles is referred to as both the U.S. Secretary of State and Trade Secretary. There is no such position as U.S. Trade Secretary. The closest that comes to it in real life is the U.S. Trade Representative. The Secretary of State is not responsible for trade matters.
Goof: Adam's hair is noticeably longer during the scene where he and Jo search Pollard's office than in it is in other scenes.
The Marx quotation isn't quite right - it should read
"The tradition of the dead generations weighs like a nightmare on the minds of
Harry and Hugo both quote it as "The dead past lies like…"
Goof: During the trip in the truck the subtitles misspell "You're welcome" as "Your welcome".
After hearing that his son saw "lizards without legs" at the zoo, Adam states that limbless lizards are snakes. Though this is most likely what his son meant, it is not entirely correct. For example, the slow-worm (Anguis fragilis) is actually not a snake, but a "lizard without legs".
The BWP are clearly modelled on the British National Party who are a far right political party in Britain.
Professor Stephen Curtis, referring to bad advances made in the world, cites "McDonalds, Andrew Lloyd Webber, and mobile phones." Ruth replies, "I think mobiles are very useful and I liked Les Mis." "Les Mis" or Les Misérables (the musical) was composed by Claude-Michel Schönberg (with a libretto by Alain Boublil and lyrics by Herbert Kretzmer), not Andrew Lloyd Webber.
The "mainline station" the second bomb was planted in is "Marylebone".
Goof: When Adam breaks into Swift's office to access his computer, the computer is a MacBook but the screen shows a typical Windows XP interface.
The word "de-encrypted" is actually just "decrypted".
When Ashworth is hanged to make it look as though he has committed suicide, he has his hands tied behind his back. How could he possibly hang himself without his hands free?
The message Ruth sends to Harry written in Morse code reads "JIC CLOSING GRID".
When Tom is undercover as 'Pete', he claims to have children called Zoe and Danny, actually the name of his two work colleagues.
During the standoff at the oil refinery, MI5 is supposedly watching a live broadcast being filmed by one soldier with a small video camera. Yet the screens at MI5 show multiple angles and cuts - basically a replay of the footage from the episode.