Continuity mistake: Season 3, Episode 68, "The Duel": When the truck first blows its tire, it is in a very muddy, watery patch of road. Subsequent scenes show the road is dry except under the truck where the truck driver is trying to jack up the truck to change the blown tire.
Ride a Cock-Horse to Laramie Cross - S4-E23
Continuity mistake: The dye job on young Clint Howard's hair is inconsistent from scene to scene. It's dark black at the start, but pales to a shade much closer to his natural blond color in many shots later on. His brown make-up (a laughable effort to make a blue-eyed Anglo kid look Hispanic) also varies, and disappears entirely in some of the covered wagon scenes.
Continuity mistake: In many of the early episodes Miss Jane drives a 1962 Plymouth convertible, but gets out of a 1963 or 1964 Dodge.
Continuity mistake: Halfway through the show, they get caught not having the boat, and McHale gets taken by boat to the commander's office. As he leaves the pier, he drops the rope on the seat next to him, they do a close-up and the rope is behind him about 5 feet away.
Continuity mistake: During his questioning inside the house, Clemens' hair goes back and forth from falling over his forehead to brushed back several times between takes. (00:05:00)
Continuity mistake: At the end of this episode Harold picks up a knife and chases Albert round the table with the knife in his right hand, but when the door bell rings the knife has disappeared.
Suggested correction: The knife doesn't disappear he actually drops it if you listen carefully.
Continuity mistake: We see that the XL18 pilot is sitting in the right seat of the cockpit. In the next shot he has changed to the left seat.