Visible crew/equipment: When Flores discovers her cell phone is missing from the hole in the wall she goes nuts, slams the stall door and kicks it in. After she is taken away there's a closeup of the stall and we can see the metal spring that was duct-taped to the bottom of the wall inside.
Continuity mistake: When Adrian stamps "denied" onto Boyle's insurance claim form, there's blank spots where there wasn't enough ink on the stamp (which would happen because he had the stamp in his pocket for a while). But then when he says "denied" and holds up the form, "denied" is all filled in fully. Also, the red border is lighter and the location has shifted down.
Factual error: In the scene, Floki walks towards a small waterfall today known as Kvernufoss. Floki is supposed to be the only inhabitant if not the entire Iceland, at least the region, as we are shown no sign of civilisation whatsoever, and as historical record tell us about Iceland in the early 800s (as the events of Vikings seem to take place). But a well beaten footpath is visible, leading to the waterfall at the end of the canyon. That path is an oft-travelled path tourists follow nowadays to reach Kvernufoss, a well-known site in the area. A path like that in Floki's time would simply not have existed (there is nothing in that canyon but that waterfall, no reason to go there if not for sightseeing) and represents a (tiny) intrusion of our modern world in a show set in the middle age Iceland. (00:37:42)