Gareth Peirce, a solicitor, is seen addressing the court. At the time of the trial, solicitors did not have "rights of audience" and could not, therefore, address the court. At that time, only barristers could do this.
In the relatively short scene where Gerry is speaking with their Atty., the guard behind Gerry alternates position and stance in each shot - head down (and looking asleep) and then moved to the side and alert in other shots.
When Paul and Gerry arrive in London they are seen walking the streets looking for Paddy's house. As they reach the street corner the street sign for 'Huskisson Street' can be seen - there is no street named this in London, only in Liverpool (the location of the take).