Jeri Ryan displays her singing talents in this episode. Her character is a torchlight songstress forced to sing for the demanding Hirogen-Nazi. She sings "That Old Black Magic" (originally published in 1942), a very popular songs during World War ll, as well as "It Can't Be Wrong" (written in 1943), which was an adaptation of "Charlotte's Theme" from Max Steiner's Academy Award-winning soundtrack for the Bette Davis film Now, Voyager (1942).
Seven of Nine's French name in the WWII simulation is "Mademoiselle de Neuf" - translating to English as "Miss of Nine." It can be assumed that her first name is "Sept," completing the translation.
Roxann Dawson was really in the final stages of pregnancy during the filming of season 4, so her pregnancy could be used effectively for this two part episode, without the necessity to film her from the chest up for the previous episodes.
The Voyager crew that took part in the WWII scenario were themselves playing Maquis - the terrorist group Voyager was pursuing which wound up sending them to the Delta Quadrant. The French anti-Nazi resistance was called the Maquis.
The text that appears on-screen, when the Doctor accesses Janeway's file, states that she was born in 2344, which would have made her twenty-seven when she took command of Voyager.