The real Lafayette Escadrille actually had a pair of lion cubs as mascots. One was indeed named "Whiskey," as in the film. The other, appropriately enough, was named "Soda."
The character of Skinner is based on the Escadrille-pilot Eugene Bullard, an American who had gone to France and worked as a boxer there. He was also a son of a slave, just like Skinner. Bullard was rejected from the Lafayette Escadrille by a prejudiced white man. He served in another escadrille in the Lafayette Flying Corps.
The character of Beagle, chose the name to escape a sordid past. The writers chose Beagle in honour of Snoopy, who as a Beagle, often fought the Red Baron in the Peanuts comic strip.
Frank Luke JR was the first airman to receive the Medal of Honor. Luke Air Force Base in Arizona is named in his honor.