Continuity mistake: When Vokar's assistant summons Tony and Doug, they are in a room with very dark walls, but the profile shot of the assistant shows a beige wall behind him.
Factual error: Raul Nimon uses a silencer-equipped revolver during his attack in the tunnel control room. In reality, a silencer on a revolver is useless, as the exploding gases from the bullet discharge (the gun blast) would exit from the space between the cylinder and gun barrel.
Continuity mistake: After the gunpowder in the cave explodes, the same keg of gunpowder is blasted out of position and rolls down twice.
Revealing mistake: The lizard crawling through the jungle in 1,000,000 B.C. brushes against and nudges a heavy tree.
Revealing mistake: The heavy boulder Tony uses to brace himself to save Nimon easily wobbles as he moves.
Continuity mistake: The boxes near the wounded sergeant switch positions after Macchiavelli shoots him.
Continuity mistake: Tony's position instantly changes as he tries to kick Doug off the bridge.
Factual error: One of the Spanish soldiers lights a torch with what appears to be a hand-held lighter. Early lighters were converted flintlock pistols (not yet invented during the time of this episode) and the earliest hand-held lighter would not be invented until three hundred years after this episode's timeline.
Revealing mistake: After the first Native American is shot in the back with the crossbow, the base used to stabilize the arrow in the back of the actor is visible underneath his clothing.
Revealing mistake: When Doug drops the torch on the gunpowder trail, the ignition of the powder is about one foot before the point where the torch is dropped.
Continuity mistake: In the opening scene of Doug and Tony's landing, Doug lands in a bush, but the next shot of the two recovering has Doug outside the bush.
Continuity mistake: After Doug drops the torch on the gunpowder trail, one of Cortez's men grabs and moves the powder keg out of the way twice.
Revealing mistake: The heavy stone table the mask is sitting on in the cave during the fight scene wobbles when bumped by the cast members.
Revealing mistake: The crossbow a Spaniard uses to shoot the elderly Indian is not loaded with an arrow.
Continuity mistake: When Doug takes cover in the cave, Nakamura fires two shots at him without chambering a new round in his bolt action rifle.
Factual error: Right at the start of the episode there is a sign visible on the side of a building that shows the German word "Warenhaus." This is a wrong translation of the English word "warehouse." The correct German word should be "Lagerhaus."
Factual error: Doug and Tony time travel to one million years B.C., where they encounter dinosaurs. Not likely. All the dinosaurs were rendered extinct several million years earlier by an asteroid strike. There weren't any left by 1-million BC. (00:29:45)
Factual error: This is one of two episodes in the series where a WW2-era German MP38/40 submachine gun was used by American forces (Master Sergeant Jiggs, in this episode) rather than an American weapon such as a Thompson submachine gun.
Other mistake: Usually Master Sergeant Jiggs and his men are posted as guards in the Time Tunnel control room at all times, but when Merlin shows up in the control room a second time, there are no guards to be seen.
Continuity mistake: At the very end of this episode, when they have just arrived in the new time, Doug is fighting a man in a turban. He loses the turban, but then the next shot, it has reappeared on his head. (00:48:54)
