Regarding stunts, Joey King did about "85-90% of what you see in the movie" so she trained how to wield a sword, throw a punch, and get right back up after taking a hit.
As well as playing The Princess in this film, Joey King plays The Prince in Bullet Train which is being released at almost the same time.
Stars Dominic Cooper and Olga Kurylenko. Kurylenko starred as a Bond girl in Quantum of Solace. Cooper played Bond creator Ian Fleming in Fleming and has been tipped to become Bond himself.
Dominic Cooper (Julius) and Olga Kurylenko (Moira) are both members of the Marvel Cinematic Universe; Dominic Cooper portrayed young Howard Stark in Captain America: The First Avenger and Agent Carter, while Olga Kurylenko played Taskmaster in Black Widow.