Continuity mistake: As you watch the chase scene after the golf course, you can tell that Left ear is driving the white mini instead of Handsome Rob. [If you watch the deleted scenes, it shows them switching places due to a gunshot wound in Rob's arm. A mistake, but explained.]
Continuity mistake: When Stella is driving in the cable van, the picture seen through her camera shows the view over the steering wheel, but when we see her, the steering wheel is much higher than the camera and would be obscuring the view.
Continuity mistake: After the minis jump out of the tunnel, Handsome Rob spins the mini around and tells Left Ear to open the door. The camera then switches to an exterior shot of the car and you can see that the rear window on the passenger side has been shattered. But in the next shot and throughout the rest of the film, the window is intact.
Continuity mistake: When Steve gets hit in the mouth by Charlie, the amount of blood in his mouth and over his teeth changes depending on the shot.
Continuity mistake: Charlize Theron parks her original Mini in a tight spot behind the Ford 4WD where she goes in front first at a fair speed. But when we see the wide shot of the Mini parked in there, it's almost bumper to bumper - there is no way anyone could have parked the Mini in that spot going in front first no matter how small the Mini is.
Continuity mistake: In the subway tunnel scene, when the trunks of the Mini Coopers are open you can see they have British licence plates. During the chase sequence the Coopers have California licence plates.
Continuity mistake: The weather changes between the first two scenes in Venice. The scene in St. Mark's Square is in fog, mist and rain, but in the next scene, supposedly taking place at exactly the same time (with Handsome Rob) there are blue skies.
Continuity mistake: When Wrench first sees Stella, the neck cover on his welder's mask is loose. The camera cuts and it's not tucked behind his head.
Continuity mistake: In the subway, all the Minis get covered in dust and grime. However, while the red and white ones stay fairly dirty, the blue one becomes spotless when he is facing off against Steve's helicopter.
Continuity mistake: After the heist, the blue Mini is seen to have a dent in the rear wing. Throughout the chase, up to when the helicopter hits the blue Mini, the dent changes size constantly.
Continuity mistake: When Charlie and Stella are talking in Stella's hotel room in Hollywood, a strand of her hair goes from over her head to hanging beside her face as the shot cuts to behind her. When it cuts to her face, the strand is over her head again, though she didn't touch her hair.
Answer: The Mini Cooper for the movie was also made as an electric car for the chase scenes in the tunnel because gas-powered cars were not allowed to be used in the tunnels. I heard that from the director's cut.