This is the first episode that Alexander Ludwig appears in as Björn.
Ecbert's anecdote about Charlamange weeping when imagining the viking age, is taken from a late 9th century biography about the emperor. It was written with the hindsight of the nearly 100 years of destructive viking raids that shook Frankia from the early 9th century and was probably an invention by the writer. During Charlamange's time, the Danish king Gudfred invaded the then Frankish province of Frisia. By the time the then elderly Charlamange had gathered his army and reached Frisia, the Danes had plundered Frisia, fought amongst themselves, Gudfred had died and his army had gone home. This demonstrated how defenseless the Frankish coats were against seaborne raids.
Many of the scenes involving Ecbert seem to be in Acqui Sulis, the Roman baths at present day Bath Spa.