Factual error: Throughout the whole show Godber, 'Bunny' Warren, McLaren, the Prison Governor and many of the guards refer to Fletcher as a Cockney. He even identifies himself as a Cockney on a number of occasions. However, in several episodes he refers to his upbringing in Muswell Hill and in this episode he refers to his having been born there - and we see his old stamping ground in that episode when he gets a weekend's compassionate leave. Nobody from Muswell Hill would ever refer to himself as a Cockney - Muswell Hill isn't even in East London!
Character mistake: "Blanco" Webb refuses parole on the grounds that, under Home Office rules, that would mean he had to admit to murdering his wife, a charge he vehemently denies. However, he accepts a pardon from the Home Office issued on the recommendation of the prison governor. Surely someone like Blanco, a man who quotes Home Office regulations by chapter, paragraph and verse, must know that a pardon is a remission of all punishment for a crime committed by the person being pardoned? By accepting a pardon he is admitting his guilt in exactly the same way as he would have been had he accepted parole.
Plot hole: Fletcher and Warren steal what they think is the History paper so Godber can study it before he sits the exam. They are adamant that he has a very short time to go through it as they have to put it back before anyone misses it. After Godber refuses to cheat by reading it Fletcher berates him, throws the paper on the cell floor and storms out. What happened to replacing the stolen exam paper?
Factual error: Lennie Godber goes before the parole board on a Monday morning and is in his cell that afternoon telling Fletcher the good news - he made parole. That is impossible. The parole board will meet, interview the prisoner, then take depositions from other interested parties - the prison governor, psychologists, and so on. They will then consider their decision and if they approve parole they will then pass their recommendation on to the Home Office who will approve or decline it. All this takes three or four days at least, so there is no way for Godber to know that day, nor to pass the news on to Fletcher.