Audio problem: When the boy and the leader of Iceland are hammering in posts and the boy is complaining that he's the heir and shouldn't have to do manual labor, there are at least two times when bad wind flutter in the microphones can be heard. It sounds like the wind clips the volume level and the audio briefly cuts out. It happens on windy film shoots, as wind screens can only prevent so much and its obviously very windy in this scene. Why this wasn't caught in post is hard to say. This is audible on the video on demand version.
Other mistake: When Amleth is having his vision of the valkyrie near the end, she appears to have dental braces on her teeth when the camera is up on her face as she is screaming.
Suggested correction: These are not braces, they are teeth "tattoos." Vikings would sometimes literally file horizontal grooves into their teeth for decorative purposes. The actress likely has not had her teeth filed for this one role so it seems what you are seeing is some sort of makeup application. But it is definitely not braces that were accidentally left in the shot.
