Revealing mistake: Season 3, Episode 68, "The Duel": The prop wash from the helicopter filming the overhead scenes are evident as everything (dust, twigs, leaves, etc.) is being blown around.
Revealing mistake: Season 3, Episode 73, "Losers Cry Deal", a GI in The Squad fires a rifle grenade at a German machine gun position in a window of a building. Not only does the rifle grenade miss the mg position, it misses where the pyrotechnic representing the rifle grenade exploding was planted.
The Letter - S5-E7
Revealing mistake: The same strawberry-blonde haired stuntman (Paul Busch) is used three times: first as an American G.I. being shot, then as a German soldier being shot, and again as another American G.I. being shot - all in the same battle scene.
The Gantlet - S5-E20
Revealing mistake: During the close combat scene between Sgt. Saunders and the German soldier, it is obviously Vic Morrow's stunt double doing the heavy action and fighting.
Revealing mistake: A German soldier steps out of a doorway ready to throw a grenade, but he gets shot, dropping the grenade a couple of feet in front of him. However, the explosion from his dropped grenade occurs from within the doorway itself.
Revealing mistake: When Sgt. Saunders throws a grenade at the German soldiers shooting at him from behind a crate, the grenade lands in front of the crate, but the explosion is actually behind the crate, where the Germans are.
Revealing mistake: Blank .30 caliber machine gun bullets are obvious as the soldier with Little John sets up and loads the weapon.
Revealing mistake: After Marsini dies, he is still breathing.
The Short Day of Private Putnam - S2-E28
Revealing mistake: 2/3 through, Beau Bridges comes upon a dead German but you can see the German breathing. Oddly, it's a fairly far shot, so he must have been breathing pretty heavily.
Revealing mistake: The German MP38/40 submachineguns have blank firing adapters on their barrels.
Revealing mistake: Blanks loaded in the German MG42 are obvious as the American tank assaults its position.
Revealing mistake: When the German soldiers are shot and fall dead into the water, one of them raises his head to take a breath, then goes back to being "dead."
Revealing mistake: The grenade Saunders tosses onto the German tank does not land where the pyrotechnics explode.
Revealing mistake: In several scenes when they show the front of the barrel of the German machine gun you can see the "blank adaptor" inside the barrel. This is inserted to not allow the gas from the cartridge to escape out the barrel but "blow back" the bolt and insert another round.
Mountain Man - S3-E1
Revealing mistake: When Saunders and his men escape from the Germans, it's supposed to be after sundown. But the entire chase scene that follows is filmed in broad daylight. (00:19:20)
Mountain Man - S3-E1
Revealing mistake: As the German chases Cage, there are multiple ski tracks in the snow from previous takes. (00:35:35)
Revealing mistake: Season 3, "The Imposter": During the march, Rick Jason slips and says, "Peabody! Bring up the rear!" He was supposed to say "Littlejohn." Peabody is the actor's real name.