The action takes place in August 1976, when Britain was in the middle of the longest heatwave of the 20th century. Police officers are shown wearing their full blue serge uniforms and even overcoats, whereas at that time it was so hot they were allowed to wear shirtsleeves and dispense with their heavy tunics.
The barristers are shown in what is called a "partners' meeting". However, barristers are independent professionals, they are not partners and are not legally allowed to form partnerships.
The younger Mr Ulrick gives the police an alibi that he was working at the Law Society library. This is not possible as the Law Society only provides facilities for solicitors. As a barrister, Mr Ulrick is not allowed to use it.
DS Miskin and DS Tarrant are firing pistols at the police shooting range. The pistols they are using are .45 calibre Colt 1911 automatics. These have never been used by a British police force.
When at the shooting range, DS Tarrant shoots one magazine, then inserts another into his Colt 1911 automatic. He then racks the slide back to cock the pistol. However, the Colt locks the slide back on an empty magazine. When he inserted a new loaded magazine, all he would have had to do was release the slide hold open catch.
When at the police shooting range, DS Miskin and DS Tarrant are both wearing ear defenders. These are necessary when firing pistols on an indoor range. Yet the range officer is not wearing any hearing protection, which would have been mandatory.