Factual error: The film states that the 42nd blockade is located on the M602 motorway, 27 miles outside of Manchester. The M602 is 3.4 miles away from Manchester at its farthest point and is barely three miles in total. It is a very short motorway. It only has 3 junctions. The filming location was actually the M1, outside Milton Keynes.
Visible crew/equipment: When Jim is looking at all the notes on the wall, the camera pans in for a close up and you can see its shadow move over Jim's shoulder. (00:12:10)
Visible crew/equipment: On the shot of Jim walking across Westminster bridge there are visible crew/members of public on the right of the shot at the end of the bridge. (00:09:30)
Other mistake: When Jim, Selena, Frank and his daughter enter the supermarket, you can notice all the fresh produce (apples, carrots etc) looking fresh. This virus has been going on for a few days now, and supermarkets get their fresh produce out immediately. After 10 days or so, give or take, the fresh produce shouldn't be looking this fresh. (00:46:00)
Answer: The metric system is used in mainland Europe, but very rarely in Britain. Road signs are still measured in miles in Britain, and distances usually are too.
He's My Brother