Morse and Dr DeBryn agree that both Pettifer and Frida sustained fractures to the right side of the skull, leading Morse to conclude that they were probably killed by the same person, and so it transpires. However, in the flashbacks to the murders Pettifer is shown being struck on the right side of his head, while Frida is struck on the left.
Mr. Yelland tells Morse that he met Frida's widowed mother, Elspeth, in London, where he had moved to look for work; he and Frida had moved back to Wantage after Elspeth's death so that they might be closer to his family. However, the telegram from the War Office notifying Elspeth of her husband's death, that Frida had kept in her mother's keepsake box, was sent to an address in Oxford, not in London.
Morse asks Monika Hicks to borrow her moped but the vehicle concerned was a Lambretta LI150 Scooter which in 1960s would have been referred to as a scooter. In the 1960s mopeds were still being manufactured, and the Honda P50 was one example; they had a very small engine plus pedals used to start the vehicle and to assist the engine when climbing hill. A Lambretta would not have been referred to as a moped in the 1960s. The scriptwriter has used 2014 language.
As the parade passes along Broad St, CCTV equipment is clearly visible.
Morse says that in 1913, Mary Richardson slashed The Rokeby Venus. This event actually took place on March 10th 1914.
The racing driver that was shooting the commercial with Diana Day is referred to as Danny Griffon, when it would have actually been Johnny Griffon, Danny Griffon's father. (See Inspector Lewis pilot)