Piers Ibbotson is billed in the credits as "Piers Gidden" (the same surname as the cast member below him).
Roland Oliver is billed in the credits as "Roland Pliver". When the credits were re-made to suit ITV's new house style, he became "Poland Oliver".
The wind blows Morse's tie as he's walking with Lewis revealing the mic that was hidden underneath it.
The 'scratch' marks on Morse car are stick on mettalic strips.
In the clipping from the Oxford Mail that Lewis is examining, the explosion and fire on board the USS Bennington occurred on 26th May 1954 - according to Morse's file, his joining date is recorded as 16th May 1964 and his promotion to Police Sergeant occurred on the 9th May 1970. Perhaps the prop designer went back a decade rather than forward - it should have been 1974 - that would make more sense given the ages of the people involved.
Inspector Morse sees a young cop on the way to evidence with the supposed murder weapon, a knife, in a plastic bag. Morse holds the knife up in the air to look at it. The knife is clean. No blood at all on it.
While Morse is looking for a medallion for the dress rehearsal of the Magic Flute, he is filmed looking in a full-length mirror. The camera man rolls into shot.