Zus and some others go to the police station to get Ampicillin to treat the pneumonia that is common in the camp. Ampicillin did not come into clinical use until 1961. Even "simple" penicillin would not have been available in Belorussia in the early 1940s.
After the air raid, when the people in the camp get ready to fight off the German infantry, one of the women is shown holding a rifle. This rifle is an M1 Garand, an American rifle which was only made the standard service rifle of the US Armed Forces in 1936. Winchester also only started delivering the rifles to Europe in 1943, at least a year after the story takes place.
During the ambush scene, Zus runs up to the German tank to throw a grenade underneath it. The grenade he is holding is shown as a German stick grenade. However when he pulls the bottom out, the sound heard is obviously that of the pin being pulled on an Allied pineapple style grenade.
During the wedding scene, the rabbi says this line in Hebrew: "Haray at mekudeshet lee beh-taba'at zo keh-dat Moshe veh-Yisrael," which translates as "Behold, you are consecrated to me with this ring according to the laws of Moses and Israel." A rabbi would have said this line minus the word "lee", meaning "to me", and then the groom would repeat the line adding in the word "lee". Otherwise it is if the rabbi was the one that got married to the bride.
In the shot, after Zus scolds Tuvia for not killing the Milkman which led to the attack, when the group is coming down the forest a reflection of some movement can be seen towards the bottom right half of the frame for almost 15 seconds.
In the scene with captured German SS-man brought to the camp, Tuvia asks for translation of his papers as well is provided with the translation of soldier's words. In reality Tuvia spoke German, which he'd learned from German soldiers during WW1.
When the German planes are bombing the camp, one plane releases a bomb over the camp. The bomb appears to explode directly under where it was released. This is incorrect as the bomb would not fall straight down. The bomb would fall at a slant.
Starting scenes shows German soldier filming the activities of others using a Bell and Howell Eyemo turret camera, used by the American military, he should have been using a Arriflex 35 II that came out in 1937 and was in wide use by German Army.
There is a scene where a young boy is playing a violin. In the credits, this boy's name is listed as Pinchas Zukerman, the now famous Israeli violinist. But, this could not be that actual Pinchas Zukerman, since he was born in 1948, three years after the war ended.
The movie talks about Israel several times, but even though the modern nation of Israel wasn't officially founded until 1948, the Jews have always referred to themselves collectively as Israel in reference to the ancient Israelite kingdom and their ancestry.
At one point in the movie, a title indicates "October 1941" yet the trees are as green as in summer-time. At this time of the year in that climate they would be half-bare and with mostly yellow leaves. Likewise, in April trees wouldn't be fully dressed with leaves yet, but rather just start to bloom.
While Tuvia Bielski is talking to the people near the campfire towards the beginning of the movie, the smoke is rising. When the camera switches, the smoke is falling down, showing that the video segment was reversed when added into the final cut.