For much of the first series Matthew Macfadyen's character (Tom Quinn) wears dark glasses, this was actually due to a burst blood vessel sometimes just visible.
At numerous times throughout series 1 notably in "One Last Dance" and "Traitor's Gate" close-ups of intelligence files show that all the information is the same and all relates to Mary Kane's terminated pregnancy from episode 1 "Thou Shalt Not Kill".
Tariq Masood: [confronting Calum]
I've met a lot of people like you. Piss-takers. You go through life finding everything so easy you think it's all a joke.
MOD Desk Officer:
They're making a map of Secret Britain. They want the public to know just how much is being kept from them. I quite agree with them, actually.
Tom Quinn: And so you just handed it over! Without a thought that they might be working against us.
What are the episodes called when aired in the US?
A
Season 1 - all the sameSeason 2 -episode 3 - Hackers = Spidersepisode 6 - President's Visit = Without Incidentepisode 8 - Military Strikes = Strike Forceepisode 9 - A Very Corporate Coup = Seventh Divisionepisode 10 - Pit of Secrets = Smoke and Mirrors