Blooper

For all the exterior shots of the Julia's car ride, the car was shown to be a black sixth generation BMW 7 series (G11/G12). However, for the escape scene as well as all other interior scenes throughout the series the team replaced the car with an older model 5th generation model BMW 7 series (F01/F02). This is most noticeable at the 38:30 mark. You can clearly see the different interior panels, wheels, tail lights and headlights for the older vehicle. This is most likely done to save cost as a 7-10 year old used BMW 7 series costs far less to purchase or rent.

Julia and PS Budd leave the PM meeting travelling in BMW 7 series 2018 model, but as soon as the sniper starts shooting in the next scene, the vehicle is BMW 7 series 2013 model.

At the end of the episode when Julia and Sgt. Budd enter their separate rooms, the scene changes to show both characters taking off their jackets. In the first scene with Julia, she clearly takes off her jacket and places it on top of a nearby sofa. During the next scene with Julia, she is shown taking off her jacket and placing it again.

The Home Secretary and David Budd are approaching 10 Downing Street and an officer at the door opens it from the outside. The door can only be opened from the inside as described in a newspaper article from 1988 - "Who has key to front door of No.10 Downing Street?"

The impact of the bullets on the Home Secretary's BMW are not consistent with a sniper firing from an elevated position. Most of the impacts shown resemble those from rounds fired from a position that would be perpendicular to the vehicle.

When Sgt. Budd is clearing up the fish and chips he has just shared with the Home Secretary it is clear that there is no gun in his holster. No armed police officer is going to just take out his gun and leave it unattended so presumably this is a result of no armourer being present on set for this particular scene.

A bodyguard's first responsibility is to guard, not to go on counter-terrorist missions. For leaving the Home Secretary in the shot-up car, taking a rifle and searching a building for a sniper, David would not have been commended, but fired immediately from his job (and maybe even prosecuted).

The sniper, who goes unidentified, is a British military veteran. Both his DNA and fingerprints would be easily available to their Intelligence Services.