Character mistake: The pilot says to his wife that the flying saucer was cigar-shaped. The actual shape was more like two dishes attached together. (00:04:45 - 00:12:20)
Factual error: The gunpowder made in the 1950's didn't produce the clouds of smoke we see whenever the police fire their weapons, but those of the 1870's did. Ed must have nicked some ammo from the Lone Ranger's property master, eh?
Continuity mistake: In scenes at the general's office, a large wall map of the U.S. is in the background. In some of the closeups you can see that it's a Santa Fe railroad map - and in others the words "Santa Fe" on the logo are taped over. (00:42:05 - 00:45:30)