Continuity mistake: As the Queen is about to take the call from Tony Blair in the kitchen you can see in front of her a few plates of food and a chopping board with two cucumbers and a black handle knife. Near the end of the scene we see an overhead shot and there is only one cucumber and the knife has disappeared as well.
Visible crew/equipment: After the Queen's jeep is stuck in the river, she glances around for a moment. The rigging of the lights and camera can be seen in the reflection of her glasses. Further, when she exits the car, the reflection of a man holding his hand to his chin can be seen in the door window. This must be a crew member, as in the next wide shot the Queen is completely alone.
Continuity mistake: When Her Majesty drives into the river, there is no road to be be seen on the other side, and her car stops about mid-river. In the next shot, when walking from the car, she is very close to the bank on the other side, and in a following shot there is a road leading up from the stalled car.
Continuity mistake: When Tony Blair and the Queen leave his final audience in London to go for a walk they exit the double doors of the chamber in Buckingham Palace and walk down the narrow halls of Balmoral Castle in Scotland (not Buckingham) and then suddenly are on the staircase of Buckingham again.
Factual error: When Tony Blair is at his home in front of a large bookcase, there are at least two books behind him that were published after 1997, when the film is set. The thick, distinctive spines of David Mitchell's 'Cloud Atlas' and Jonathan Franzen's 'The Corrections' can both be seen.