Sölvi Fannar who plays Richard Lionheart is the son of DOP Viðar Jónsson, who has been filming since 1967.
Richard Coeur de Lion very rarely spoke English, although born in England he was raised in France and spoke mostly French and Occitan.
The song Ja nus hons pris that Sölvi Fannar sings in Casus Belli is actually written by Richard Lionheart who was a poet and troubadour.