Continuity: During the fight inside the spider, West wraps one of Loveless' men in a chain and kicks him out the door. You clearly see that the chain comes completely off the its roll and falls to the ground, presumably with the body. Yet later on in a wide shot of the spider you can see the body and chain still suspended from the spider. Then when it crashes, West uses the hanging body to save himself.

Continuity: When Gordon and West are chasing Loveless in the train. They pass through a tunnel. On the other side of the tunnel, Loveless has elevated his train on crutches to hide as West and Gordon's train goes under Loveless' train.  During the shot where you look through to the end of the tunnel there are no crutches showing where Loveless is hiding. In the very next scene you are looking back into the tunnel from the end and the crutches of Loveless' train are now there at the end of the tunnel. Then Loveless' train lowers back onto the track.

Factual error: When they show the capital building in Washington DC it is still under construction, but it was actually finished in 1864 - 5 years before the movie's set.

Visible crew/equipment: When Jim West is hanging by the rains of the horse you can see the rider's boot as Jim West is telling the horses to back up.

Other: As the tarantula approaches the first small desert town (when Lovelace orders Grant to surrender the government to him), look at the townsfolk. Not one of them pays any attention to the noisy, giant metal spider as it lumbers towards the town. In fact, none of them react at all until the first building explodes. I guess giant spider robots were a common sight in the middle of the 19th century West.

Revealing: In the scene where Will Smith first jumps aboard the rear of Loveless's train, as he climbs onto the roof of it you can see contrails from a jet aeroplane in the sky (top left).

Continuity: In the scene where the "Do not push" button is pushed for the first time, Jim West is launched on to the pool table and strapped down by two harnesses. However the lower harness shoots out between his legs, only strapping his right leg. In the next shot both legs are strapped down.

Continuity: While Artemis Gordon is doing his "martial arts warm-up," Jim West is in a relaxed fighting stance from one camera angle, but just standing up from another.

Continuity: When Gordon and West are in the White House (after the real president Grant walks in), Gordon is shown removing his false stomach and tucking his shirt in. In one scene, the shirt is almost totally tucked in, in the next scene, the shirt is pulled back out of his pants. He then tucks the shirt back in again (for the second time).

Revealing: It's painfully obvious that CGI backgrounds in panorama shots are fake. A good example is just after they get their magnetic collars off and are walking through the desert.

Revealing: When Loveless removes the pin connecting the cart to the horses with the nitro in crates, it begins to roll down the cliff. There are already tracks for the cart to follow as it goes off the edge.

Continuity: In the shot where McGrath punches West in the face, he has the hearing thing in his ear. Next shot, when he runs away, he doesn't have the hearing thing in his ear.

Continuity: In the scene where Jim West is walking up to the White House we can see different shadows: the ones generated by the bodies of people in the street go one way, but we can clearly see that the white house dome has light coming from the same direction as the people's shadows are going. The White House's shadow goes in the right direction for the light.

Factual error: Unlike in the movie, President Grant did not actually attend the "golden spike" ceremony at Promontory, Utah.

Factual error: After the demonstration of his tank, Loveless requests 1,000 kg of each country who wants to join him in his little war and bring it within four days at his secret lab. Now, since most of them were from Europe, how can they ever bring that amount of money over to the U.S.? It would take weeks to cross the ocean, let alone days until they reach the secret lab.

Factual error: West and Gordon are outfitted with massively powerful magnetic collars. Somehow the two collars don't interact with each other at all until they try to remove them, when they prove able to attract each other from at least 20 meters. Gordon rationalizes this by saying that they accidentally reversed one magnet's polarity, but if this were so then the magnets should have originally opposed each other with the same force, instantly throwing each other apart as soon as they were brought within meters of each other. Nonsensical.

Continuity: When West and Gordon are being chased by Loveless in their trains they are riding on a straight (as we can see from their over the shoulder shots). Yet when Loveless fires the cannon at them, the shot shows the back of the train and a small hill being hit by the shot, the train is turning a corner as this happens. But when we see the O-T-S camera shot again, the train is back on a straight track. Where did the hill come from?

Factual error: The amount of nitroglycerin in just one bottle at the beginning of the movie would be enough to level the whole brothel. Yet, when a cart loaded with bottles of nitro (or at least one full crate) goes downhill and explodes, it only makes a big fireball.

Continuity: When the giant metal spider approaches, the bridge moves from side to side and up and down. But in the next close-up everybody on it is standing upright with no problems.

Continuity: During the brothel scene, Loveless is seen near the cart containing nitro-glycerine. We see him pull the hinge out of the cart and the cart rolls down the hill and into the brothel. Now there's two things wrong with this scene. First, it wasn't a small hill, it was a small cliff that was near the brothel. And second, where did the horses pulling the cart go?