Trivia: Allegedly Roald Dahl once tuned into a TV airing of this film while staying at a hotel. Due to having sworn never to see the movie it took a good 15 minutes before he realized what he was watching and immediately changed the channel in disgust.
Trivia: The 'Golden Goose Egg' scene was shot on Julie Dawn Cole's (Veruca) 13th birthday.
Trivia: The foam sprouting from the machine Wonka takes through the Wonkawash was actually the foam from a number of fire extinguishers.
Trivia: The tinker that startles Charlie outside the gates of the factory quotes from the poem "The Fairies" by William Allingham. "Up the airy mountain, Down the rushing glen."
Trivia: Augustus' father is stated to be the town's most prominent "parve butcher." "Parve" means "lacking meat and milk", therefore there is no such thing as a "parve butcher."
Trivia: The daffodil that Gene Wilder eats at the end of the pure imagination song was not made of rice paper or anything nice it was made out of wax, that he had to chew and then spit out when the camera stopped rolling.
Trivia: None of the kids were allowed to see the chocolate factory set beforehand, so that their looks of surprise upon seeing it were genuine. But Julie Dawn Cole, who played Veruca, recently admitted that when she was on the set a few weeks earlier to record her song, a stagehand let her take a look at it.
Trivia: Denise Nickerson received thirteen cavities in her teeth because of all the gum she had to chew on set as Violet. (According to her, there was no sugarless gum back when the movie was filmed).
Answer: Closed circuit security was invented in 1942 and came into common use in the late 60s and early 70s. Beyond that, Wonka could have had Oompa Loompas monitoring the group or simply noticed that they were gone and guessed.
Greg Dwyer