Jamie picks up Ronsel during a pouring rainstorm, but when Ronsel enters the truck, he's completely dry.
When Jamie comes home from the war, a package of Lucky Strike "Green" is visible on the table. Lucky's packaging was switched to white in 1942; even in the middle of nowhere, there's no way a three-year-old package of cigarettes would not have been consumed, especially with rationing.
Laura narrates the numbers for the lock she's opening, where she says the combination is 8-30-62, for the Confederate victory at the Battle of Richmond. August 30, 1862 was actually the Confederate victory at the Battle of Second Manassas, which occurred about 90 miles north of Richmond in Virginia.
When Jamie is in the European brothel, a Foley background sound has been added of another couple having sex off-screen. However, the off-screen prostitute is moaning in English, and her voice has a distinctly modern L.A. accent which did not exist in Europe during this era.
When Henry and Laura are waiting to meet Jamie at the train station, you can see a modern silver car drive past the entrance behind Laura.
The film opens in the evening with the brothers desperately trying to finish digging a grave before the storm arrives (there is no obvious reason for the rush). The rain arrives and the hole fills with mud. The next scene shows them putting the coffin in the hole, the next day, with no mud.
The first McAllan child would not have been born any earlier than late 1939. Yet the two young girls happily greet by name their "Uncle Jamie" after he returns from four years of war. Neither child would have been old enough to remember Jamie before his departure in 1941.