The film combines various visual effects techniques to create accurate and recognizable historical worlds : full CG landscapes and buildings (London), CG landscapes on StageCraft video wall (Valhalla, Spartan battle…), green screen and matte painting, 3D animation (the reverse arrow and the phantom blade during the French revolution). Each stunt and camera movement had to be precisely choreographed to blend everything together in post-production. It was especially the case for perfect match-cuts (the hand transition, the Caesar/Venice transition…)