When Gordon is being tortured, his missing leg changes from his left to his right one and back again between shots.
(at around 1h 17 mins) When the land-mine that Richard is stepping from explodes you can clearly see that the explosion takes place in a completely different part of the forest; the tree on the left side of the screen which wasn't there before, the soldiers balancing over the horizontal-tree are completely gone, the background lighting is completely different).
(at around 46 mins) During the paint ball scene, we see characters get shot with paint. In the scene with dialog the paint is missing from their clothes.
(at around 35 mins) Harris pours himself water twice. He grabs the glass when Maggie says "Everyone calm down", then again when she says "Jill come with me".
(at around 37 mins) When Jill knocks her glasses off the chair in the bedroom, the legs are covered in dust when she picks them up and puts them on. She walks to the bathroom to get a drink of water, the dust has gone.
(at around 31 mins) The Russian troops in the flashback are wearing currently issued German Flecktarn camouflage.
(at around 2 mins) When George is hanging upside down it is clearly visible that his nostrils are blocked, this to prevent blood from seeping into them.
The files Harris found contain the same text in Russian, including the same passport numbers. In addition, a passport number in Russia contains ten digits, not eight.