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.
Revealing mistake: In the scene where Chitty is taking off from the castle, Caracticus looks down at the toymaker and Peter and says, "Bye bye". If you look closely, right in front of them, a boy runs across holding a stick he stole from one of the cavalrymen. He is waving it around and you can tell it's fake because it flops around like rubber.
Trivia: Julie Andrews was the actress chosen to play the part of Truly Scrumptious. However, as revealed in "Julie Andrews: An Intimate Biography", Ms. Andrews had grown tired of being typecast in playing the same type of roles in Sound of Music and Mary Poppins. She turned down the part.