Factual error: Several of Ragnar's relatives are called "Lothbrok" through the series (most notably, Rollo and Ubba), but Lothbrok was not a family name. The vikings did not use family names at all, though they did use personal sobriquets (such as "Ironside", "the Boneless" or "Finehair"). "Lothbrok" was Ragnar's nickname only. A more appropriate sobriquet for any of his sons would be "Ragnarsson" (son of Ragnar).
Factual error: The 'rudder' oar is fitted on the Port (left) side of Ragnar's new boat. The starboard of all boats and all floating vessels is named as a result of the steering oar always being fitted on the right hand side of the boat and it is depicted on the Bayeux tapestry as reference. It is very natural also for right handed people and for anybody who ever used a Canadian canoe.