Plot hole: After the first attack on the U96 the captain decides to resurface after sunset. However when they do resurface it's broad daylight.
Plot hole: In the scene where Colby is discussing tactics with the team, Pele interrupts and takes the chalk from Colby and says "Hatch gives me the ball here, I do this, this, this, this, goal" while drawing a line on the blackboard to indicate dribbling from one end of the pitch to the other. At that point in the film, Hatch was only the trainer, not the goalkeeper.
Plot hole: The movie is allegedly set about ten years after the death of the German soldiers, since the daughter of one soldier is in her early teens. But none of the items in the scenery look like they're out of the fifties.
Plot hole: David couldn't have seen Sutherland's photos because Sutherland hadn't had time to develop them yet. Even if he did, it would have been difficult to find a lab that wouldn't turn him in as a spy. Overall, it would have been much safer to have the film processed in Germany.