- Ash Face: Sgt. Brophy has one after a grenade thrown by Buster explodes in the American trench.
- Contrived Coincidence: Buster meets his old valet, a German, in the opposite trench.
- Description Cut: An American officer tells his French counterpart "We are proud to be with you in your sunny France", and the camera cuts to show Buster's unit marching through a Biblical rainstorm. Later, when the men have gone into the trenches, their officer says "This is a quiet sector." Cue immediate heavy German bombardment.
- Drill Sergeant Nasty: Sgt. Brophy, the hot-tempered drill sergeant who repeatedly bawls out poor bumbling Elmer.
- Extra! Extra! Read All About It!: Used word-for-word as Elmer's ineffectual courting of Mary is interrupted by newsboys selling papers announcing American intervention in the war.
- Fainting: Elmer and several of his comrades do this when Sgt. Brophy, during drill, gives an overly detailed description of bayoneting someone.
- Gentlemen Rankers: Elmer is a very rich young man who blunders into enlisting by mistake (see Upper-Class Twit below).
- Happy Ending: Not only has Buster married Mary and started his own business with his Army buddies, but Sgt. Brophy is his janitor.
- Idle Rich: Elmer lives off his family's money, which is one reason Mary rejects him.
- Mathematician's Answer: Elmer tends to give these.Army recruiter: Who's the nearest relative?
Elmer: My sister. She lives right around the corner.
- Not What It Looks Like: Buster, tossed out of his billet, wanders into a random cottage and finds a bed. It turns out the next morning to be the second bed in a young woman's room, and her father is pissed.
- Shell-Shocked Veteran: Used for the closing gag, weirdly enough. The sound of a rivet gun sends Buster and all his old Army friends diving for cover, and causes Sgt. Brophy to shift from servile janitor back to antagonistic Drill Sergeant Nasty.
- Upper-Class Twit: Dimwitted Elmer, who enlists in the Army by accident when he thinks he's hiring a chauffeur. The scene where a doctor at the recruiting center asks him to strip, and Elmer finally realizes something's wrong, is a highlight of the film.