Beginning with this episode, Enterprise was shot with digital cameras rather than on traditional film.
In the weapons demonstration film clip, an alien is shown blowing up a building with a rifle. This footage is from The Killing Game (1998), another World War II themed two-part episode, in which J. Paul Boehmer played a Nazi.
With the addition of this episode, Enterprise became the first Star Trek series to start a 4th season without having any change in the cast since its pilot episode.
This episode takes place in 1944. Along with Assignment: Earth (1968) (which takes place in 1968), this is one of only two "Star Trek" episodes to take place entirely in the 20th Century. Furthermore, both episodes take place mostly in and around New York City.
Daniels' condition in this episode originally appeared in Shattered (2001), where Chakotay was taken out of temporal sync and was in a state of temporal flux.