In curing Tolkien's case of trench fever, the Legends are potentially creating a huge time aberration, as his illness was likely the reason why he survived the war and went on to become a successful writer. The disease forced Tolkien to be relieved of combat duty and sent home, after which almost his entire battalion was killed in action. Having been cured, he would have likely returned to active duty and been killed alongside his comrades.
Tolkien would not give a radio frequency in megahertz. The term wasn't introduced until later. It was then megacycles per second.
Nate says that the church of Amiens was built in the 1600s. Wiki says in was built almost entirely between 1220 and 1270.
From 32:55 -Rip's request for a battlefield cease-fire is broadcast in English which all the German soldiers magically understand.
When everyone is giving Mick a hard time about divulging plans to Snart, Stein is one of the loudest and most aggressive towards Mick. Stein has been helping Mick work through his issues in seeing fake Snart and for him to blatantly accuse and not offer any explanation is such a huge character plot hole and lazy writing.