In the season 3 finale at the end, Captain Archer is seen in the Nazi hospital with burns on his face. As season 4 begins, Captain Archer is seen healed from the burns, but still healing from cuts and bruises. The timing is supposed to be the next day, as Vosk wants to interrogate Archer as soon as possible.
When the small convoy taking Archer to be interrogated is attacked by Resistance fighters, Archer escapes. As he is confronted by a fighter the sound of a hammer being cocked is heard. A second later the fighter holds a 1911 pistol is pointed at Archer the hammer is down. For the 1911 to fire the hammer must be back.
When Enterprise approaches New York City it is attacked by Stuka dive bombers. By 1944, Stukas were rarely used, since newer fighter planes and even jets like the ME-262 had replaced the old Stuka bomber design. However, this adventure takes place in a world whose history diverged from ours in 1916.
Sickbay doors open before T'Pol touches the panel. Occurs when she is on her way to talk to Daniels after he regains consciousness.
When Archer, Alicia and the others meet the alien in the alleyway, the alien's hand is lit up as he backs away from them and it is a normal human (probably Caucasian) hand rather than the gray of the alien's face.
Alicia Travers tries repeatedly to fire a Colt 1911 .45 pistol, after it's run out of ammo. It clicks repeatedly. This type of pistol doesn't do that.
It is never explained how Archer survived the destruction of the Xindi planet-killer.
The large map of United States on the wall has labels in German language. However, two names are incorrectly labeled: California and Pazifisches Meer. In German language, California is spelled as "Kalifornien" (only US state to have different spelling in German), and Pacific Ocean is translated as "Pazifischer Ozean".
When reading the requisition form, the German officer says 86 metric tons of aluminum plating. This is the American pronunciation. In Europe, it is pronounced and spelled aluminium.