Factual error: The three plutonium spheres appear to be about six inches (15 cm) in diameter. At that size, and at 19.3 grams per cubic centimeter, they would weigh about 102 kilos (220 pounds), far too heavy to be carried around so easily.
Factual error: When Ethan enters Ramstein Airbase, he drives a BMW with a German license plate that can't possibly exist. The only German license plates starting with digits are for official diplomats. There is none starting with 881, the highest is 205 anyway. Another mistake is that even if it was a car of a diplomat, the license plate would have additional lettering next to the country letter D (for Deutschland), in Germany that would be CC or CD.
Factual error: The white van in London has a registration mark BT 34873K that would never be possible in the UK. Yes they've just arrived from mainland Europe, but no country in Europe uses that format on registrations, combined with the style, type and display of the actual plate.
Factual error: After a helicopter warning signal says pull up, Ethan pulls back on the cyclic control. All that would do is slow the helicopter by changing the blade angles. He should have pulled up on the collective between the seats. (01:56:15)
Factual error: The number plate on the white van that Ethan, Luther, Benji and Elsa are travelling in has 8 digits instead of the 7 of a normal UK number plate.
Suggested correction: The number plate is the Norwegian format. Likely acquired whilst in mainland Europe.
The text on the side of the van says "London and the Home Counties" so driving on Norwegian plates would be incongruous and draw attention. Surely something you would not want in a covert van. If you're picking apart the van, why no phone number or website for the fake company. Again, it just looks wrong.
That doesn't change the fact that it has a valid number plate. Within the EU vehicles can be used in any country, provided they meet the local legal requirements. In the case of the UK, that is being up to date with any servicing and the vehicle being insured. It is not a movie mistake that the van exists or that it could be in London. They used a van they had access to.