Revealing mistake: In one of the war flashbacks Stephen carries the wounded Dodge through a trench. They pass by a screaming pig, but in slow motion you can see that it's just a motionless carcass. (01:01:05)
Revealing mistake: Billy buys about 20 bars of ice-cream, carries them home, and is shown lying in the yard, nibbling slowly on almost the last of them which is still cold and solid. (01:18:20)
Revealing mistake: In one of the war flashbacks Stephen approaches a helicopter that is about to take off. You hear the rotor move fast, but the grass around the helicopter is completely still. (01:02:00)