When Stonehouse and wife + secretary are having a picnic in the outdoors in Australia and then the police arrive to arrest him, the police cars are all left hand drive. This scene is meant to take place in Australia which is a country with right hand drive cars. When they set off in the aerial shot they drive on the correct Australian side (left) of the road.
The exterior of the Houses of Parliament started to be cleaned in 1981. In the 1970s the colour of the building was very much darker than it appears today and as shown.