After the hospital near Szpilman's hideout bursts into flames, a German holds two Polish resistance fighters at gunpoint. When they escape, the German fires his rifle, a bolt-action Karibiner 98k, which then makes the sound of a shotgun being pumped.
When Szpilman is forced to leave his first hiding place after breaking the dishes, he has significant stubble on his face. However, when he reaches Dorota's apartment in the next scene, he's clean shaven.
When Szpilman is told he has to leave the first apartment he's hiding in, his hair is parted and hanging down either side of his face. In the next shot, when he sits down to try to smoke the cigarette, his hair is combed back with no part visible.
When Szpilman is forced to leave his first hiding place after breaking the dishes, he encounters an angry woman is the hallway who asks for an identity card and seems ready to turn him in as a Jew. He is forced to rush past her to escape. But once he's outside the front door he seems relatively calm--she couldn't just chase after him?
When Szpilman watching situation on street from his 2nd shelter, one of captured couple start running from soldier. The man apparently escaped, but woman was shot to her back. It took couple seconds from shot until she finally dropped to her knees and lean forward dead, so from the camera viewpoint the blood stream on her back should draw number "7", not a straight line slightly upward (agains gravity).
The German sergeant opens the sack of beans with a bayonet that is not German issue. It appears to be a Turkish Model 1890 bayonet. However, in war it's common for soldiers to use a weapon stolen or bought from another country if their own supplies are low.
Near the end of the movie, Szpilman leaves the house where he has been hiding for a while. Warsaw is completely destroyed, and all buildings are in shambles, but all the streetlight poles are perfectly straight.
Szpilman walks in formation along the street with a group of Jewish workmen. A German officer selects various men and executes them one by one by shooting them in the head. As the last man is shot, the hollow sound of a spent shell casing striking the ground is heard, but a complete cartridge with the bullet falls to the ground. A closer look will reveal it is actually a spent blank cartridge.