The shorts that the men are wearing in the beginning when they swimming are alittle too modern looking.
In the beginning when Agnar and Freya are swimming, he lifts her up out of the water and she's wearing a modern day bikini. Women didn't wear bathing suits back then, let alone bikinis.
When the beast is shown hanging by his neck supposedly dead his lair is torched and his body is showed burning. But later when he comes back to life he is unscathed.
Eric is hit over the head and bleeding profusely. Later no bandage or even a wound is shown.