Jules Grove shows McDonald and Dodds the mysterious note that he found, with the text "De jonge mogen sterven, de oude moet.", which is Dutch and means "The young ones may die, but the old one must." However, when McDonald and Dodds later show supposedly the same note to Loz Addington during her interrogation or to Mrs. Burchard, the text of the note and the handwriting are significantly different. The Dutch text now reads "De jongen mogen sterven, de ouden moeten sterven.", which means "The young may die, the old must die.", and is written in block capitals instead of cursive.
When Archie Addington reads his speech at the press conference he folds the paper in to a small piece when he finishes. In a following shot the paper is shown opened out in his hands again.
The crown on the left epaulette on Chief Superintendent Ormond's uniform moves from straight to skewed and back again between scenes. (The same costume error also occurred in the first programme.)
The title of the episode and the speech behind it (that humans are allotted only a billion heartbeats in a lifetime) are incorrect. With an average heart rate of 60 beats per minute and an average lifespan of 70 years, anyone can expect their heart to beat 2,207,520,000 times in a lifetime.
While Dodds holds the helmet inverted, the thin spike shoots out upwards. So it would have come downwards when worn, and pierced the victim's shoulder, not his neck.
The watch that Dodds finds and calls Omega Seamaster is in fact an Omega Speedmaster, they are two completely different models.
In the opening sequence, which was supposed to be the Formula One race at Monza in Italy, shows the cars with grooved rain tires fitted even though the weather is clear and the track is dry.
Addington says that at the race in Watkins Glen weather blew in from the Atlantic, causing the death of the Dutch driver. Watkins Glen is more than 200 miles inland, and coastal weather never comes anywhere near.
There could be no certainty that a thin spike piercing the neck would cause massive internal bleeding. It might be more likely to instead pierce the jugular vein, in which case there would have been blood everywhere.