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!
Factual error: S 49/E 5-12: Victoria and Ashland's wedding was in Italy. While in Italy the characters made calls back to Genoa City, Wisconsin and always apologized for the time difference and for disturbing them. In fact, it should have been the other way around since there is a 7-hour time difference with Italy being ahead. There were scenes where they claiming it was morning or night in Genoa City when it should have been morning or night based on the time of the scenes in Italy.
Factual error: The armed robbery is reported by the radio call as happening in "4014 Nostrand Avenue", which is a real street in Brooklyn. However, the first detectives to respond to the dispatch identify themselves as being from "Manhattan South" (makes sense, Kojak being a Lieutenant of the fictional 11th Manhattan South precinct), and the rest of the episode is set obviously in Manhattan. That's many miles away.