When Rocky meets Nancy in Paris he boasts of his 33 victories. Three days later, back at the squadron, he has 41. Somebody didn't read the script very closely.
A page-a-day calendar is used to show the passage of time, but the months are out of alignment. One sequence shows "September 16" and the next page is "October 17." This is repeated again seconds later, in reverse order, when it shows "October 25" followed by "September 26."
Even though the film takes place in 1917-1918, all of Elizabeth Allan's clothing and hairstyles are strictly early 1930s, the year the film was produced.
Early in the film, a man enters the garden party and yells "We're in it at last! President Wilson has declared war!" American presidents can NOT declare war; they must ask for a declaration of war from the U.S. Congress. This was voted on and approved by Congress on April 6, 1917.