Revealing mistake: As Jango fires the machine gun, the ammunition chain hanging from it is loaded on both sides, and it doesn't move. Also the belt has different sizes of cartridges in it. (00:45:30)
Revealing mistake: When Django exits the saloon after having been in there to drink and have sex with Maria, his boots are already covered with wet mud. His boots should have dry, caked-on mud. This means they did multiple takes of this scene, but they didn't bother to clean off the boots between takes. (00:29:15 - 00:29:40)
Revealing mistake: In some of the shots showing the muddy town street, tracks from modern rubber tires can be seen. (00:28:00)
