In the final of the episode, after Kwenthrith has poisoned Burgred, all the assembled characters are seen pouring out their wine goblets.
One second sees Ragnar and Ecbert doing so, Ragnar's goblet sideways, Ecbert's upright. The very next second shows Ragnar's upright, and Ecbert's sideways; with no time having passed in between.
One second sees Ragnar and Ecbert doing so, Ragnar's goblet sideways, Ecbert's upright. The very next second shows Ragnar's upright, and Ecbert's sideways; with no time having passed in between.
Ragnar and his crew were in England for the summer while the women stayed behind in Kattegat. However Siggy drowned in the winter when saving Ragnars sons after they fell through the ice on a frozen lake. Even if it was a cold summer there would be no frozen lakes in Norway in summer.
Harbard mentions Oslofjorden, but this fjord was called Fold or Foldin in the era depicted in the show.