Arabic graffiti next to the word "uprising" is a misspelling of "intifadah" ('uprising' in Arabic). It was written with the letter dal instead of dad. The correct spelling of intifadah uses the letter dad; it also ends with a ta marbuta, not an alef.
When Theo has agreed to help the Fishes by getting transit papers for Kee and follows an agent to what turns out to be a meeting with Julian on a Double Decker Bus, the bus he chases and presumably boards is a thinly disguised MCW Metrobus, dating from circa 1982, with characteristic boxy, old-fashioned appearance. However, when we cut to the bus interior, it is that of a Wrightbus Gemini model, dating from 2003 or later - this model is much curvier in shape than the Metrobus. Once Julian and Theo leave the bus, it passes by, and we see that it is indeed now the modern vehicle from which they have alighted, carrying the manufacturer's stylised 'W' moulding on the rear panel.
When Theo and the two women escape from the farmhouse, it is dark while he is disabling the cars. Yet minutes later, after they have freewheeled down the dirt track, there is already bright morning sunshine.
When Nigel yells at Alex to take his pills, Alex takes the first pill and drinks some water. The next camera shot of Alex shows him taking a second pill but his glass has more water in it than before. Also, in these same three camera swaps Nigel's pill box moves closer to his wine glass, which now has less wine than the previous shot, even though Nigel's position doesn't change.
During the first continuous shot following Theo leaving the coffee shop, the reflection on the coffee shop door shows the faces of a patrol officer and a group of people just outside the door and walking to the right. Yet when the camera exits the shop, the cop does not appear in view as expected from the reflection, rather the cop and group instantly appear further down the street to the right.
After the attack on the Fiat Multipla (carrying Luke, Julian, Theo, Miriam, and Kee), when they stop for the police, just as Theo gets out, out his door you can momentarily see part of the framework for the elaborate roof camera rig. As the view crosses the door pillar it disappears; this is apparently used to transition to another shot.
Theo enters Battersea Power Station, after crossing the Thames to speak with his cousin, but when he arrives, the car enters a place that is obviously Tate Modern. Afterward, the scenery returns to what it would be, had it been Battersea Power Station.
When Theo, Kee and Miriam move between Syd's vehicle and the bus to take them to Bexhill, the M3 motorway is visible at the top right of the frame. This scene was filmed at Chobham test track in Surrey (the control tower for the test track also features prominently here) but traffic on the motorway is visible underneath the bridge which swoops around to the right of the frame.
When trying to escape from the farm the car has a flat battery, so they roll the car to attempt the push start it. When it does start you can hear that the car is an automatic. You cannot push start a car with an automatic gearbox.
When entering Jasper's house for the first time, an obviously retouched photo (with the headline "MI5 DENY INVOLVEMENT IN TORTURE OF PHOTOJOURNALIST") shows Janice Palmer holding a camera with a large lens. The hand holding the weight of the lens shows a right hand but should be a left hand. It is unlikely that she would have a little finger that is longer than her index finger, as shown in the photo.
At both the outer and inner gate of the camp (start and end of bus trip) the bus passes underneath a signpost reading "HOMELAND SECURITY - BEXHILL REFUGEE CAMP". Though located far from one another the signposts look exactly the same - down to every spot and mark of the heavily applied artificial weathering.
The goof items below may give away important plot points.
When Theo and Kee get into the boat at Bexhill Water Authority, it is in a level body of water in a tunnel that is clearly not tidal. Yet they emerge seconds later into the sea, which is of course tidal, without apparently having made any descent.
When Kee reveals her pregnancy to Theo in The Fishes' barn, her left arm is across her chest and her right hand below her pregnant belly. During the cuts between Theo's reaction and Kee's body, her arms are switched (with her right arm across her chest and left hand below her belly), then back again after the next cut.