Continuity mistake: Truly crashes into the pond three times: first when the kids are playing in the road and she takes them home, second on the day of the picnic when she says she has nothing else to do and will go on the picnic too, and third at the end of the film when Potts finds out he is rich. In the second of these three, when Mr. Potts carries Truly from her car in the pond, the end of the ribbons on the back of her dress gets soaked in mud, but when you see her again at the beach there is no sign of the dirt.
Continuity mistake: Dick Van Dyke is trying to show his new whistle sweet to Mr Scrumptious, the sweet factory owner. His dog is tied up to a bicycle outside. When his dog hears the whistle he knocks over the bicycle whilst trying to get free and runs up the steps. In the immediate shot following the bicycle is standing up again.
Continuity mistake: In the "Chitty on the water" scene, when Chitty has deployed a float her wheels become horizontal. In the far way shots, the wheels aren't moving. In the close up shots done in the studio, the horizontal wheels are spinning and there is no visible raft beneath the boat.
Continuity mistake: When the two spies try to capture Chitty by parking their open van under the railway bridge, then dropping a canvas screen down over the top so it looks like the road under the bridge is clear, as Lord Scrumptious's car hits the screen and tears through it, you can see that there is nothing parked on the other side. The van is gone. Yet the following shot establishes the fact that the trap has worked successfully; the car has gone through the screen and ended up in the back of the van.