Revealing mistake: When the target's iPhone rings and Christopher Chance answers it, he swipes his finger across the bottom of the screen, which is the regular gesture to answer a call on the iPhone. Trouble is that we see the screen at the time, and it's not showing an incoming call, just some sort of list - he swipes his finger over nothing of any significance at all.
Revealing mistake: Near the end of the battle at the end of the episode, we see some Japanese troops coming out from the jungle. The Marines then shoot a machine gun, killing them. But pay attention to the ammo belt. All the bullets are blanks. (00:38:50)