On two occasions, the German radio room (as a holo simulation) can be seen. The two-way radio in that room is indeed a World War II radio, but it is an American World War II radio, not a German military radio. The radio shown had (has) a US Army designation called "BC-312" or "BC-342". On the radio, four bright indicator lights can be seen, which were not present on the original BC-312 radio. They were added by the props department for effect.
To be fair to the makers, the episode also depicts a genuine BC-611 radio which is shown in Chakotay's army tent (the walkie talkie on his desk), and Tom Paris uses a genuine BC-1000 WWII radio on two occasions. These two WWII American army radios are shown in their correct configurations (including accessories) and are indeed of WWII vintage, so I was impressed to see these two items depicted as factually correct.
Chakotay (as a US Army Major) states that he's going to call in an "RAF airstrike." As a member of the US Army. if he did call in an airstrike. it would be easier and quicker to get the USAAF (Army Air Force) to do the job than it would the Air Force of another nation, especially since they used different radios.
Captain Miller purports to be a member of US 5th Armored Infantry, but no such unit existed in the American army during the second world war. The shoulder patch is of the US 29th Infantry Division.
Torres says that they stole the weapons from the Germans, yet their weapons (M1 Garand, Colt M1911) are all American.
Janeway lures the Hirogen hunter to a part of Voyager where the holo emitters have been destroyed. His WW2 rifle disappears yet she picks up another holo rifle and walks away.
When Turanj arrives in Engineering to stop the Alpha Hirogen from ending the simulation, the Alpha can be seen with a hole in his Klingon uniform before Turanj even fired a single round from the rifle. Clearly a mistake by the costume department. The hole in his uniform shouldn't have been seen until after the first shot had been fired. Even when the second shot was fired there should have been a 2nd hole in his uniform but there is only 1.
In the French town, a Citroën 2CV car can be seen driving around on several occasions. Although the car is indeed French, the 2CV model did not exist during World War II. The very first version of it came out in 1948. In addition, the model shown is of much later vintage, not older than 1960.
Janeway tells Chakotay (who still believes that he is a US Army major) that she is "Gung Ho" when it comes to her "people" (meaning the crew). While the term "Gung Ho" was developed during WWII, it was done so by US Marines in the Pacific and actually wouldn't become common vernacular until after WWII. (While there was a Hollywood film 'Gung Ho!': The Story of Carlson's Makin Island Raiders (1943), it wasn't successful.)
At one point an Hirogen orders a subordinate to help him seal the hatch, yet on numerous occasions Janeway opens and closes the hatch with no effort. Considering the Hirogen are meant to be superior in strength, they, not Janeway, struggle with the hatch.
It's shown at one point that Voyager has been turned into 1 big holodeck with bulkheads and floors have been removed but where did they go and how did they rebuild voyager if these were missing,