Revealing mistake: When Varna is sliding down the rope and gets shot in the back with an arrow, the safety pad under her clothes protrudes noticeably.
Continuity mistake: When we first see Sonja, she lies with her right arm fully extended along her body. From the back shot, it's not.
Other mistake: When Sonja is being raped, modern fillings are visible on her teeth.
Revealing mistake: During the fight at the shrine, a woman throws a warrior on top of a pile of rocks, and the rocks squeeze down, revealing they're made of foam. When the warrior falls on the floor, the rocks reinflate back to their previous shape.