Audio problem: Season 3, Episode 68, "The Duel". Sometimes the tank's co-axial machine gun is firing, but no gunfire sound is heard.
The Raider - S4-E16
Audio problem: When the jeep peels out on the grass, it makes a screeching tires-on-asphalt sound.
Audio problem: Several times the German tank fires its co-ax turret machine gun. There is gunfire flashing, but no machinegun sound.