Hanna was raised by her father, in isolation, near the Arctic Circle, intensely trained to be an assassin. In a close-up of Hanna she has pierced ears, it is unlikely from her upbringing that she would have this.
In the freight yard scene, when Hanna kills one of the men after her, she slashes him several times across the chest, and then body slams him up against the wall. When she pulls away and runs off, there is no blood on her shirt or face.
The bridge in the background where Eric leaves the water, is the Femer bridge in Germany. When he comes up he kills two Danish police officers and later is seen lying on a bed reading a postcard, where the address says Aalsgaarde, which is a city in the northern part of Zealand, Denmark.
The following FAQ entries may contain spoilers. Only the biggest ones (if any) will be covered with spoiler tags. Spoiler tags have been used sparingly in order to make the page more readable.
Q
How did Hanna launch her arrow at Marissa without a bow?
A
At one point during the final chase scene, you see Hanna (Saoirse Ronan) lean down and snatch a length of bungee cord from one of the rides. She uses this to launch the arrow.
Q
Why did Hanna need to trigger the switch, instead of she and Erik just going to kill Marissa?
A
It was part of their plan. Erik (Eric Bana) trained Hanna specifically for the task of being captured in order to kill Marissa (Cate Blanchett) on the inside and then escape to meet up with him later at Grimm's house. The switch allowed Marissa's team to find them (when Hanna was ready) and take her back to their base.