During the scenes shot in the pub near the beginning, for the first while the wall clock is stopped for several minutes at 6:30, and later it is stopped for several minutes at 7:10.
When the railway crossing gates close as Barnaby and his passenger arrive near the end of the story the sound played is that of a US railroad crossing (a bell-like sound). In reality, UK railway crossings make a high pitched "wee-wah" sound.
After 23 minutes and 25 seconds, Eddie opens a card which is signed "from The Welcoming Commitee".
The correct spelling of the word is committee.
When a camera obscura pans across its field of view, the image also rotates on the viewing table. Here, the image mostly stayed the same orientation while the scene panned. Obviously a video projection simulating a camera obscura.
The character of "Dave Ripert" was killed in episode 4.03 (The Electric Vendetta)