The main character bears the same name as the last carrier pigeon sent by Commandant Raynal from Fort Vaux on 4 June 1916, during the battle of Verdun. It arrived, deadly wounded with its message, and was in 1929 given a plaque at the Fort with the words "Mort pour la France."
In the movie members of the French Resistance, play "Non, je ne regrette rien" sung by Édith Piaf. However World War II was over twelve years before the song was even written.
Valiant calls his instructor "Sir". In fact the instructor has the Rank of Flight Sergeant. You wouldn't call an NCO "Sir". You address him by his Rank (in this case Flight or Flight Sergeant).