When pathologist DeBryn examines the severed lower arm of Richard Parker, he says that the humerus has been cut clean through. The humerus is the bone in the upper arm. There are two bones in the lower arm, the radius and ulna.
Sgt, Strange describes his pint of Double Diamond as lager, but Double Diamond was actually India Pale Ale.
The enclosure shown couldn't have contained a tiger. Tigers weigh between 500-700lbs and is nearly all muscle and bone. The enclosure shown was made of light wood and chicken wire. Not only could it not have contained a tiger, even attempting to lock the tiger inside the enclosure would likely have proven to be fatal.
On the map, there is a place name "Crevecouer" which is taken from the French, meaning "heart break" except it is wrongly spelled. It should be "Crevecoeur"
When Morse examines the LP that Strange has gifted him, a bar coded sticker is visible on the upper right of the back cover. Bar codes weren't introduced until the 1970's.
This episode is set in 1967. In the campfire scene, the girl is playing an acoustic guitar made by Crafter guitars, a company that wasn't founded until 1972.