One of the Danish warriors with a distinct Cossack-style haircut is seen in the front line facing the Saxons and is shown in close-up as the first casualty of the battle. However, a minute later he is seen next to earl Ragnar at another part of the battlefield alive.
When the children are in the woods, Uhtred hears a twig snap as Sven approaches. The closed captioning displays the sound as 'gun cocks'.
The bird shown at the beginning is a Harris's hawk. It couldn't have been used in falconry at that time in Britain because it is native to the Americas.
Ragnar's ship has a sign on it that says, 'Wind Viper' in modern English with Latin letters.
The tack on the horses, particularly the bridles with their perfect stainless-steel, well machined buckles and a variety of bits, were modern.
The Lord of Northumberland claims that they were once kings of all the lands between the river Tweed and Tyne. Bernicia actually stretched from the Forth to the Tees. The Tweed didn't become the border with Scotland until much much later. Although at this time Scotland did not exist and the north was under a transformation from a Pict kingdom into a Gaelic kingdom. Scotland or Alba didn't come about until much later.
The Lord of Northumberland mispronounces 'Bebbanburgh', pronouncing 'burgh' as 'berg'. The correct pronunciation is closer to 'bra' or 'bruh'. The current Northumbrian dialect has changed very little over the centuries, and it is unlikely that there has been a shift in pronunciation of the word. For example, vowels in Northumberian are still pronounced similar to Frisian (or North Sea Germanic). Place names ending with 'ingham' are still pronounced as in Old English 'in-jam'.